重点讲解：
1. be made out of
用…（制成）；由…（建成）；
例句：Many items in daily use are made out of plastic.
有很多日常生活用品是塑料制的。
2. be supposed to do sth.
认为；觉得；相信；
例句：He is commonly supposed to be foolish.
他是公认的傻瓜。
3. think back
回忆；回想；
例句：Even now I don't like to think about it.
就算是现在我也不愿回想起我的童年。
4. to tell the truth
说实在的；坦白说；
例句：To tell the truth, this is all Greek to me.
说实话,我对此一窍不通。
5. in case
以备；以防；免得；
例句：We allowed a margin of twenty minutes in case the bus was late.
我们预留二十分钟宽裕时间，以防汽车晚点。
