重点讲解：
1. in advance
提前；事先；
eg. British Summer Time is one hour in advance of Greenwich Mean Time.
英国的夏季时间比标准时间快一小时。
eg. The booking office sells tickets 3 days in advance.
售票处预售3天的票。
2. book up
满号；订光；
eg. I could not get even one ticket since all the seats were booked up.
我一张票也弄不到，所有的座位都已预定一空。
eg. By now, every place must be booked up.
现在这时候到处都被订满了。
3. depend on
取决（于）；有赖（于）；
eg. The cooking time needed depends on the size of the potato...
所需的烹饪时间取决于土豆的大小。
eg. What happened later would depend on his talk with De Solina...
日后之事将有赖于他与德索利纳的谈话结果。
eg. How much it costs depends upon how much you buy.
价钱取决于你买多买少。
