E

　　71.each other 互相，彼此

　　They help each other in work. 他们在工作中互相帮助。

　　They congratulated each other on their success. 他们互相庆祝成功。

　　72.either…or 或……或，不是……便是

　　The letter may arrive either today or tomorrow. 信或者今天或者明天到。

　　Either he or you are right. 不是他就是你对了。

　　73.engage in 从事，忙于

　　He is engaged in writing a book. 他忙着写一本书。

　　He is engaged in writing a letter of invitation. 他在忙着写邀请信。

　　74.enjoy oneself 玩得愉快，感到快乐

　　Did you enjoy yourself at the party? 聚会过的愉快吗?

　　We enjoyed ourselves heartily at the dance. 我们在舞会上玩的十分愉快。

　　75.even if/though 即使，纵然

　　I will go even if it rains cats and dogs. 即使下大雨我也去。

　　You won't mind even if he doesn't come. 即使他不来，你也不要介意。

　　76.expert in 擅长

　　She is expert in playing the piano. 他擅长弹钢琴。

　　Hi is said to be expert in English speech. 据说他擅长英文演讲。

　　77.familiar with 熟悉，通晓

　　Make yourself familiar with the foreign customs soon. 要尽快熟悉外国的风俗。

　　Only practicing more can help you to be familiar with your work. 只有多实践，你才会熟悉工作。