双语例句
's a useful introduction to an extremely complex subject.
这是对一门极为复杂的学科的有益入门教程。
oduction of electronic point-of-sale systems is improving efficiency.
引进销售点电子系统提高了效率。
balance, the book is a friendly, down-to-earth introduction to physics.
总而言之，这是一本通俗而务实的.物理入门书。
4.A prolonged drought had necessitated the introduction of water rationing
由于持续干旱，用水需要实行配给了。
explains in the introduction how he gathered the data.
他在引言里解释了他是如何收集到数据的。