introduction可数吗

　　例句：

　　By way of introduction , let me give you the background to the story.

　　作为引言，我先来介绍一下故事的背景。

　　The camera has undergone only two minor tweaks since its introduction.

　　这款相机自推出以来只经过两次小的改进。

　　Millions of words have been written about the introduction of the euro.

　　已有上百万的文字论及欧元的引入。

　　Introduction of electronic point-of-sale systems is improving efficiency.

　　电子售货系统的引进提高了工作效率。

　　A prolonged drought had necessitated the introduction of water rationing.

　　一场持续的干旱使定量供水的引进成为必需。