Index: src/wp-admin/edit.php
===================================================================
--- src/wp-admin/edit.php	(revision 31836)
+++ src/wp-admin/edit.php	(working copy)
@@ -247,7 +247,8 @@
 $bulk_messages = array();
 $bulk_messages['post'] = array(
 	'updated'   => _n( '%s post updated.', '%s posts updated.', $bulk_counts['updated'] ),
-	'locked'    => _n( '%s post not updated, somebody is editing it.', '%s posts not updated, somebody is editing them.', $bulk_counts['locked'] ),
+	'locked'    => ( 1 == $bulk_counts['locked'] ) ? __( '1 post not updated, somebody is editing it.' ) :
+	                   _n( '%s posts not updated, somebody is editing them.', '%s posts not updated, somebody is editing them.', $bulk_counts['locked'] ),
 	'deleted'   => _n( '%s post permanently deleted.', '%s posts permanently deleted.', $bulk_counts['deleted'] ),
 	'trashed'   => _n( '%s post moved to the Trash.', '%s posts moved to the Trash.', $bulk_counts['trashed'] ),
 	'untrashed' => _n( '%s post restored from the Trash.', '%s posts restored from the Trash.', $bulk_counts['untrashed'] ),
@@ -254,7 +255,8 @@
 );
 $bulk_messages['page'] = array(
 	'updated'   => _n( '%s page updated.', '%s pages updated.', $bulk_counts['updated'] ),
-	'locked'    => _n( '%s page not updated, somebody is editing it.', '%s pages not updated, somebody is editing them.', $bulk_counts['locked'] ),
+	'locked'    => ( 1 == $bulk_counts['locked'] ) ? __( '1 page not updated, somebody is editing it.' ) :
+	                   _n( '%s pages not updated, somebody is editing them.', '%s pages not updated, somebody is editing them.', $bulk_counts['locked'] ),
 	'deleted'   => _n( '%s page permanently deleted.', '%s pages permanently deleted.', $bulk_counts['deleted'] ),
 	'trashed'   => _n( '%s page moved to the Trash.', '%s pages moved to the Trash.', $bulk_counts['trashed'] ),
 	'untrashed' => _n( '%s page restored from the Trash.', '%s pages restored from the Trash.', $bulk_counts['untrashed'] ),
Index: src/wp-admin/includes/ajax-actions.php
===================================================================
--- src/wp-admin/includes/ajax-actions.php	(revision 31836)
+++ src/wp-admin/includes/ajax-actions.php	(working copy)
@@ -379,7 +379,7 @@
 		// Here for completeness - not used.
 		'id' => $comment_id,
 		'supplemental' => array(
-			'total_items_i18n' => sprintf( _n( '1 item', '%s items', $total ), number_format_i18n( $total ) ),
+			'total_items_i18n' => sprintf( _n( '%s item', '%s items', $total ), number_format_i18n( $total ) ),
 			'total_pages' => ceil( $total / $per_page ),
 			'total_pages_i18n' => number_format_i18n( ceil( $total / $per_page ) ),
 			'total' => $total,
Index: src/wp-admin/network.php
===================================================================
--- src/wp-admin/network.php	(revision 31836)
+++ src/wp-admin/network.php	(working copy)
@@ -413,8 +413,16 @@
 		}
 		$num_keys_salts = count( $keys_salts );
 ?>
-	<p><?php
-		echo _n( 'This unique authentication key is also missing from your <code>wp-config.php</code> file.', 'These unique authentication keys are also missing from your <code>wp-config.php</code> file.', $num_keys_salts ); ?> <?php _e( 'To make your installation more secure, you should also add:' ) ?></p>
+	<p>
+		<?php
+			if ( 1 == $num_keys_salts ) {
+				_e( 'This unique authentication key is also missing from your <code>wp-config.php</code> file.' );
+			} else {
+				_e( 'These unique authentication keys are also missing from your <code>wp-config.php</code> file.' );
+			}
+		?>
+		<?php _e( 'To make your installation more secure, you should also add:' ); ?>
+	</p>
 	<textarea class="code" readonly="readonly" cols="100" rows="<?php echo $num_keys_salts; ?>"><?php echo esc_textarea( $keys_salts_str ); ?></textarea>
 <?php
 	}
Index: src/wp-admin/network/themes.php
===================================================================
--- src/wp-admin/network/themes.php	(revision 31836)
+++ src/wp-admin/network/themes.php	(working copy)
@@ -146,14 +146,18 @@
 			if ( ! isset( $_REQUEST['verify-delete'] ) ) {
 				wp_enqueue_script( 'jquery' );
 				require_once( ABSPATH . 'wp-admin/admin-header.php' );
+				$themes_to_delete = count( $themes );
 				?>
 			<div class="wrap">
-				<?php
-					$themes_to_delete = count( $themes );
-					echo '<h2>' . _n( 'Delete Theme', 'Delete Themes', $themes_to_delete ) . '</h2>';
-				?>
-				<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php echo _n( 'This theme may be active on other sites in the network.', 'These themes may be active on other sites in the network.', $themes_to_delete ); ?></p></div>
-				<p><?php echo _n( 'You are about to remove the following theme:', 'You are about to remove the following themes:', $themes_to_delete ); ?></p>
+				<?php if ( 1 == $themes_to_delete ) : ?>
+					<h2><?php _e( 'Delete Theme' ); ?></h2>
+					<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'This theme may be active on other sites in the network.' ); ?></p></div>
+					<p><?php _e( 'You are about to remove the following theme:' ); ?></p>
+				<?php else : ?>
+					<h2><?php _e( 'Delete Themes' ); ?></h2>
+					<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'These themes may be active on other sites in the network.' ); ?></p></div>
+					<p><?php _e( 'You are about to remove the following themes:' ); ?></p>
+				<?php endif; ?>
 					<ul class="ul-disc">
 					<?php
 						foreach ( $theme_info as $theme ) {
@@ -162,7 +166,11 @@
 						}
 					?>
 					</ul>
-				<p><?php _e('Are you sure you wish to delete these themes?'); ?></p>
+				<?php if ( 1 == $themes_to_delete ) : ?>
+					<p><?php _e( 'Are you sure you wish to delete this theme?' ); ?></p>
+				<?php else : ?>
+					<p><?php _e( 'Are you sure you wish to delete these themes?' ); ?></p>
+				<?php endif; ?>
 				<form method="post" action="<?php echo esc_url($_SERVER['REQUEST_URI']); ?>" style="display:inline;">
 					<input type="hidden" name="verify-delete" value="1" />
 					<input type="hidden" name="action" value="delete-selected" />
@@ -170,9 +178,15 @@
 						foreach ( (array) $themes as $theme ) {
 							echo '<input type="hidden" name="checked[]" value="' . esc_attr($theme) . '" />';
 						}
+
+						wp_nonce_field( 'bulk-themes' );
+
+						if ( 1 == $themes_to_delete ) {
+							submit_button( __( 'Yes, Delete this theme' ), 'button', 'submit', false );
+						} else {
+							submit_button( __( 'Yes, Delete these themes' ), 'button', 'submit', false );
+						}
 					?>
-					<?php wp_nonce_field('bulk-themes') ?>
-					<?php submit_button( _n( 'Yes, Delete this theme', 'Yes, Delete these themes', $themes_to_delete ), 'button', 'submit', false ); ?>
 				</form>
 				<?php
 				$referer = wp_get_referer();
@@ -254,14 +268,29 @@
 
 <?php
 if ( isset( $_GET['enabled'] ) ) {
-	$_GET['enabled'] = absint( $_GET['enabled'] );
-	echo '<div id="message" class="updated"><p>' . sprintf( _n( 'Theme enabled.', '%s themes enabled.', $_GET['enabled'] ), number_format_i18n( $_GET['enabled'] ) ) . '</p></div>';
+	$enabled = absint( $_GET['enabled'] );
+	if ( 1 == $enabled ) {
+		$message = __( 'Theme enabled.' );
+	} else {
+		$message = _n( '%s theme enabled.', '%s themes enabled.', $enabled );
+	}
+	echo '<div id="message" class="updated"><p>' . sprintf( $message, number_format_i18n( $enabled ) ) . '</p></div>';
 } elseif ( isset( $_GET['disabled'] ) ) {
-	$_GET['disabled'] = absint( $_GET['disabled'] );
-	echo '<div id="message" class="updated"><p>' . sprintf( _n( 'Theme disabled.', '%s themes disabled.', $_GET['disabled'] ), number_format_i18n( $_GET['disabled'] ) ) . '</p></div>';
+	$disabled = absint( $_GET['disabled'] );
+	if ( 1 == $disabled ) {
+		$message = __( 'Theme disabled.' );
+	} else {
+		$message = _n( '%s theme disabled.', '%s themes disabled.', $disabled );
+	}
+	echo '<div id="message" class="updated"><p>' . sprintf( $message, number_format_i18n( $disabled ) ) . '</p></div>';
 } elseif ( isset( $_GET['deleted'] ) ) {
-	$_GET['deleted'] = absint( $_GET['deleted'] );
-	echo '<div id="message" class="updated"><p>' . sprintf( _nx( 'Theme deleted.', '%s themes deleted.', $_GET['deleted'], 'network' ), number_format_i18n( $_GET['deleted'] ) ) . '</p></div>';
+	$deleted = absint( $_GET['deleted'] );
+	if ( 1 == $deleted ) {
+		$message = __( 'Theme deleted.' );
+	} else {
+		$message = _n( '%s theme deleted.', '%s themes deleted.', $deleted );
+	}
+	echo '<div id="message" class="updated"><p>' . sprintf( $message, number_format_i18n( $deleted ) ) . '</p></div>';
 } elseif ( isset( $_GET['error'] ) && 'none' == $_GET['error'] ) {
 	echo '<div id="message" class="error"><p>' . __( 'No theme selected.' ) . '</p></div>';
 } elseif ( isset( $_GET['error'] ) && 'main' == $_GET['error'] ) {
Index: src/wp-admin/network/users.php
===================================================================
--- src/wp-admin/network/users.php	(revision 31836)
+++ src/wp-admin/network/users.php	(working copy)
@@ -24,10 +24,10 @@
 	?>
 	<h2><?php esc_html_e( 'Users' ); ?></h2>
 
-	<?php if ( count( $users ) > 1 ) : ?>
+	<?php if ( 1 == count( $users ) ) : ?>
+		<p><?php _e( 'You have chosen to delete the user from all networks and sites.' ); ?></p>
+	<?php else : ?>
 		<p><?php _e( 'You have chosen to delete the following users from all networks and sites.' ); ?></p>
-	<?php else : ?>
-		<p><?php _e( 'You have chosen to delete the user from all networks and sites.' ); ?></p>
 	<?php endif; ?>
 
 	<form action="users.php?action=dodelete" method="post">
@@ -103,10 +103,10 @@
 	/** This action is documented in wp-admin/users.php */
 	do_action( 'delete_user_form', $current_user );
 
-	if ( count( $users ) > 1 ) : ?>
+	if ( 1 == count( $users ) ) : ?>
+		<p><?php _e( 'Once you hit &#8220;Confirm Deletion&#8221;, the user will be permanently removed.' ); ?></p>
+	<?php else : ?>
 		<p><?php _e( 'Once you hit &#8220;Confirm Deletion&#8221;, these users will be permanently removed.' ); ?></p>
-	<?php else : ?>
-		<p><?php _e( 'Once you hit &#8220;Confirm Deletion&#8221;, the user will be permanently removed.' ); ?></p>
 	<?php endif;
 
 	submit_button( __('Confirm Deletion'), 'delete' );
Index: src/wp-admin/plugins.php
===================================================================
--- src/wp-admin/plugins.php	(revision 31836)
+++ src/wp-admin/plugins.php	(working copy)
@@ -283,12 +283,20 @@
 						}
 					}
 					$plugins_to_delete = count( $plugin_info );
-					echo '<h2>' . _n( 'Delete Plugin', 'Delete Plugins', $plugins_to_delete ) . '</h2>';
 				?>
-				<?php if ( $have_non_network_plugins && is_network_admin() ) : ?>
-				<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php echo _n( 'This plugin may be active on other sites in the network.', 'These plugins may be active on other sites in the network.', $plugins_to_delete ); ?></p></div>
+				<?php if ( 1 == $plugins_to_delete ) : ?>
+					<h2><?php _e( 'Delete Plugin' ); ?></h2>
+					<?php if ( $have_non_network_plugins && is_network_admin() ) : ?>
+						<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'This plugin may be active on other sites in the network.' ); ?></p></div>
+					<?php endif; ?>
+					<p><?php _e( 'You are about to remove the following plugin:' ); ?></p>
+				<?php else: ?>
+					<h2><?php _e( 'Delete Plugins' ); ?></h2>
+					<?php if ( $have_non_network_plugins && is_network_admin() ) : ?>
+						<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'These plugins may be active on other sites in the network.' ); ?></p></div>
+					<?php endif; ?>
+					<p><?php _e( 'You are about to remove the following plugins:' ); ?></p>
 				<?php endif; ?>
-				<p><?php echo _n( 'You are about to remove the following plugin:', 'You are about to remove the following plugins:', $plugins_to_delete ); ?></p>
 					<ul class="ul-disc">
 						<?php
 						$data_to_delete = false;
Index: src/wp-admin/upload.php
===================================================================
--- src/wp-admin/upload.php	(revision 31836)
+++ src/wp-admin/upload.php	(working copy)
@@ -219,12 +219,12 @@
 <?php
 $message = '';
 if ( ! empty( $_GET['posted'] ) ) {
-	$message = __('Media attachment updated.');
+	$message = __( 'Media attachment updated.' );
 	$_SERVER['REQUEST_URI'] = remove_query_arg(array('posted'), $_SERVER['REQUEST_URI']);
 }
 
 if ( ! empty( $_GET['attached'] ) && $attached = absint( $_GET['attached'] ) ) {
-	$message = sprintf( _n('Reattached %d attachment.', 'Reattached %d attachments.', $attached), $attached );
+	$message = sprintf( _n( 'Reattached %d attachment.', 'Reattached %d attachments.', $attached ), $attached );
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'detach', 'attached' ), $_SERVER['REQUEST_URI'] );
 }
 
@@ -234,18 +234,33 @@
 }
 
 if ( ! empty( $_GET['deleted'] ) && $deleted = absint( $_GET['deleted'] ) ) {
-	$message = sprintf( _n( 'Media attachment permanently deleted.', '%d media attachments permanently deleted.', $deleted ), number_format_i18n( $_GET['deleted'] ) );
+	if ( 1 == $deleted ) {
+		$message = __( 'Media attachment permanently deleted.' );
+	} else {
+		$message = _n( '%d media attachment permanently deleted.', '%d media attachments permanently deleted.', $deleted );
+	}
+	$message = sprintf( $message, number_format_i18n( $deleted ) );
 	$_SERVER['REQUEST_URI'] = remove_query_arg(array('deleted'), $_SERVER['REQUEST_URI']);
 }
 
 if ( ! empty( $_GET['trashed'] ) && $trashed = absint( $_GET['trashed'] ) ) {
-	$message = sprintf( _n( 'Media attachment moved to the trash.', '%d media attachments moved to the trash.', $trashed ), number_format_i18n( $_GET['trashed'] ) );
+	if ( 1 == $trashed ) {
+		$message = __( 'Media attachment moved to the trash.' );
+	} else {
+		$message = _n( '%d media attachment moved to the trash.', '%d media attachments moved to the trash.', $trashed );
+	}
+	$message = sprintf( $message, number_format_i18n( $trashed ) );
 	$message .= ' <a href="' . esc_url( wp_nonce_url( 'upload.php?doaction=undo&action=untrash&ids='.(isset($_GET['ids']) ? $_GET['ids'] : ''), "bulk-media" ) ) . '">' . __('Undo') . '</a>';
 	$_SERVER['REQUEST_URI'] = remove_query_arg(array('trashed'), $_SERVER['REQUEST_URI']);
 }
 
 if ( ! empty( $_GET['untrashed'] ) && $untrashed = absint( $_GET['untrashed'] ) ) {
-	$message = sprintf( _n( 'Media attachment restored from the trash.', '%d media attachments restored from the trash.', $untrashed ), number_format_i18n( $_GET['untrashed'] ) );
+	if ( 1 == $untrashed ) {
+		$message = __( 'Media attachment restored from the trash.' );
+	} else {
+		$message = _n( '%d media attachment restored from the trash.', '%d media attachments restored from the trash.', $untrashed );
+	}
+	$message = sprintf( $message, number_format_i18n( $untrashed ) );
 	$_SERVER['REQUEST_URI'] = remove_query_arg(array('untrashed'), $_SERVER['REQUEST_URI']);
 }
 
Index: src/wp-admin/users.php
===================================================================
--- src/wp-admin/users.php	(revision 31836)
+++ src/wp-admin/users.php	(working copy)
@@ -216,11 +216,17 @@
 <div class="wrap">
 <h2><?php _e('Delete Users'); ?></h2>
 <?php if ( isset( $_REQUEST['error'] ) ) : ?>
-<div class="error">
-	<p><strong><?php _e( 'ERROR:' ); ?></strong> <?php _e( 'Please select an option.' ); ?></p>
-</div>
+	<div class="error">
+		<p><strong><?php _e( 'ERROR:' ); ?></strong> <?php _e( 'Please select an option.' ); ?></p>
+	</div>
 <?php endif; ?>
-<p><?php echo _n( 'You have specified this user for deletion:', 'You have specified these users for deletion:', count( $userids ) ); ?></p>
+
+<?php if ( 1 == count( $userids ) ) : ?>
+	<p><?php _e( 'You have specified this user for deletion:' ); ?></p>
+<?php else : ?>
+	<p><?php _e( 'You have specified these users for deletion:' ); ?></p>
+<?php endif; ?>
+
 <ul>
 <?php
 	$go_delete = 0;
@@ -236,7 +242,11 @@
 	?>
 	</ul>
 <?php if ( $go_delete ) : ?>
-	<fieldset><p><legend><?php echo _n( 'What should be done with content owned by this user?', 'What should be done with content owned by these users?', $go_delete ); ?></legend></p>
+	<?php if ( 1 == $go_delete ) : ?>
+		<fieldset><p><legend><?php _e( 'What should be done with content owned by this user?' ); ?></legend></p>
+	<?php else : ?>
+		<fieldset><p><legend><?php _e( 'What should be done with content owned by these users?' ); ?></legend></p>
+	<?php endif; ?>
 	<ul style="list-style:none;">
 		<li><label><input type="radio" id="delete_option0" name="delete_option" value="delete" />
 		<?php _e('Delete all content.'); ?></label></li>
@@ -379,7 +389,12 @@
 		case 'del':
 		case 'del_many':
 			$delete_count = isset($_GET['delete_count']) ? (int) $_GET['delete_count'] : 0;
-			$messages[] = '<div id="message" class="updated"><p>' . sprintf( _n( 'User deleted.', '%s users deleted.', $delete_count ), number_format_i18n( $delete_count ) ) . '</p></div>';
+			if ( 1 == $delete_count ) {
+				$message = __( 'User deleted.' );
+			} else {
+				$message = _n( '%s user deleted.', '%s users deleted.', $delete_count );
+			}
+			$messages[] = '<div id="message" class="updated"><p>' . sprintf( $message, number_format_i18n( $delete_count ) ) . '</p></div>';
 			break;
 		case 'add':
 			if ( isset( $_GET['id'] ) && ( $user_id = $_GET['id'] ) && current_user_can( 'edit_user', $user_id ) ) {
Index: src/wp-includes/class-wp-customize-manager.php
===================================================================
--- src/wp-includes/class-wp-customize-manager.php	(revision 31836)
+++ src/wp-includes/class-wp-customize-manager.php	(working copy)
@@ -1351,11 +1351,17 @@
 		$menus          = wp_get_nav_menus();
 		$num_locations  = count( array_keys( $locations ) );
 
+		if ( 1 == $num_locations ) {
+			$description = __( 'Your theme supports one menu. Select which menu you would like to use.' );
+		} else {
+			$description = sprintf( _n( 'Your theme supports %s menu. Select which menu appears in each location.', 'Your theme supports %s menus. Select which menu appears in each location.', $num_locations ), number_format_i18n( $num_locations ) );
+		}
+
 		$this->add_section( 'nav', array(
 			'title'          => __( 'Navigation' ),
 			'theme_supports' => 'menus',
 			'priority'       => 100,
-			'description'    => sprintf( _n('Your theme supports %s menu. Select which menu you would like to use.', 'Your theme supports %s menus. Select which menu appears in each location.', $num_locations ), number_format_i18n( $num_locations ) ) . "\n\n" . __('You can edit your menu content on the Menus screen in the Appearance section.'),
+			'description'    => $description . "\n\n" . __( 'You can edit your menu content on the Menus screen in the Appearance section.' ),
 		) );
 
 		if ( $menus ) {
Index: src/wp-includes/theme-compat/comments.php
===================================================================
--- src/wp-includes/theme-compat/comments.php	(revision 31836)
+++ src/wp-includes/theme-compat/comments.php	(working copy)
@@ -23,8 +23,16 @@
 <!-- You can start editing here. -->
 
 <?php if ( have_comments() ) : ?>
-	<h3 id="comments"><?php	printf( _n( 'One Response to %2$s', '%1$s Responses to %2$s', get_comments_number() ),
-									number_format_i18n( get_comments_number() ), '&#8220;' . get_the_title() . '&#8221;' ); ?></h3>
+	<h3 id="comments">
+		<?php
+			if ( 1 == get_comments_number() ) {
+				printf( 'One Response to %2$s',  '&#8220;' . get_the_title() . '&#8221;' );
+			} else {
+				printf( _n( '%1$s Response to %2$s', '%1$s Responses to %2$s', get_comments_number() ),
+					number_format_i18n( get_comments_number() ),  '&#8220;' . get_the_title() . '&#8221;' );
+			}
+		?>
+	</h3>
 
 	<div class="navigation">
 		<div class="alignleft"><?php previous_comments_link() ?></div>