重点讲解：
1. be supposed to do sth.
认为；觉得；相信；
eg. When a ladder is propped against the wall, it is supposed to be bad luck to walk underneath it.
当梯子靠墙支架时，从下走过被认为是有坏运气。
eg. In fact, stress isn't a bad thing it is often supposed to be.
事实上，压力并不像人们所认为的那样是一件坏事。
2. thanks for sth./doing sth.
向…表示谢意；感谢；
eg. Thanks for all your help.
谢谢你帮我们做的一切。
eg. Thanks for inviting us, it was a lovely evening.
感谢您邀请我们度过了这样一个愉快的夜晚。
3. used to do sth.
过去常常；过去曾；
eg. She used to work at her laptop until four in the morning.
她从前经常用手提电脑一直工作到凌晨4点。
eg. People used to recoil from the idea of getting into debt.
过去人们不能接受欠债这种事情。