我們先來看一個故事，來猜猜文章中和人身體有關的短語的含義吧。
Last year my English class was full of characters. Thats a polite way of saying it had some unusual people that Ill never forget. One student was such a hard worker that he learned all the idioms in our book by heart. He was always saying things like m on cloud nine, or m green with envy. We never knew if he meant what he said or if he was just practicing English. Another student had a sweet tooth. She would bake lots of bread and cakes and bring them to every class for us to share during breaks. Two students met in the class and fell head over heels in love. We were all invited to their wedding and had a great time. Then there was a student who was always pulling someones leg. For example, one day before class, he put a long homework assignment on the board and made us think that the teacher had given it. We all had long faces until the teacher came in. Then we realized that someone had played a joke on us.
現在看看這些成語在例句中的用法，你能猜出它們的含義嗎?
by heart
I know all my friends telephone numbers by heart. I never have to look in the telephone book.
含義是是熟記，背誦
have a sweet tooth
I know you have a sweet tooth, so I bought you a box of chocolates.
