13. Sorry, I have to go to class now.
不好意思，我得去上课了。
还能这样说：
I am sorry, but I'm going to attend classes.
Sorry, I have to take lessons right now.
应用解析：
get a class 毕业考试优等;
in clas 在上课中;
in the same class 同一类型的，同等的;
take a class of 担任……班的教师
14. If you have no other things, you may hang up the phone.
如果你没有其他事，你就可以挂电话了。
还能这样说：
If you have told me what you want, you can end the conversation.
You can ring off if you don't have other business.
应用解析：
I'll be hanged!
真想不到!会有这种事!
15. I feel tired now. What about making a call another day?
我很累了，明天再打好吗?
还能这样说：
I get tired right now. Could we contact another day?
I am exhaused at this moment. Do you mind calling back another day?
应用解析：
be tired out 累得要死，累极了;
feel tired 觉得疲倦;
be tired of 厌倦
16. She burst into tears after hanging up the phone.
电话结束时她突然哭了起来。
还能这样说：
She cried loudly when she rang off.
She couldn't help crying outright when she ended the conversation.
应用解析：
go burst 失败;
be bursting to do 渴望，急着要做;
at one burst 一阵，一口气，一举
17. See you tonight.
晚上见。
还能这样说：
See you this evening.
See you in the evening.
谚语：
Outsiders see more than insiders.
当局者迷，旁观者清。