重点讲解：
1. keep on 重复；继续；
例句：A business must stay in the black to keep on.
一个公司必须盈利才能维持。
2. shut up （使）住口；（使）闭嘴；
例句：She gave me a gentle nudge in the ribs to tell me to shut up.
她用肘轻轻捅了一下我肋骨让我住口。
3. tend to do sth. 往往会；经常就；
例句：Most old people tend to cling to old ideas.
多数老年人常常墨守成规。
4. in general 总的来说；总体上来看；大体上；
例句：In general her work has been good,but this essay is dreadful.
总的说来，她的作品不错，不过这篇文章糟透了。
5. by the way 顺便地；附带说一句；
例句：Oh, by the way, there is a telephone message for you.
噢，对了，有你一个电话口信
