重点讲解：
1. get a crush on sb.
迷恋；爱慕某人；
eg. It takes only a minute to get a crush on someone, but it takes a lifetime to forget someone.
爱上某个人可能只需要几分钟时间，但是要忘记一个人可能要一生的时间。
eg. Some teenager girls got a crush on the film star.
十几岁的女孩子一下子就爱上了那个电影明星了。
2. just in case/in case of
以备；以防；免得；
eg. Extra boiling water should be kept at hand just in case it is needed.
身边应多准备一些开水，以备不时之需。
eg. In case of fire, ring the alarm bell.
如遇失火，请按警铃。
3. be meant to
注定（或肯定）要…；
eg. John was constantly reassuring me that we were meant to be together.
约翰不断安慰我说，我们注定要在一起。
eg. Life is always meant to be unpredictable.
生活注定就是一波三折的。
4. be supposed to do sth.
应当，应该，须；
eg. Don't be too curious about things you are not supposed to know.
对于你不应该知道的事情别去好奇地打听。
eg. You are supposed to be on the lookout for things like that.
这类事情你本该小心点才是。