L: 这课真是枯燥无味。我最讨厌晚上上课，每次上完课，我都感到很累。
M: That's right. Even though it's not that late, I'm ready to hit the sack!
L: 你说什么？你要去捅一个口袋？Sack不是麻袋吗？我以为你很累了，而你现在要去运动？
M: No, no. It's a colloquial saying. I mean I'm going to bed. Sack, here means bed, and hit means going to.
L: 噢，原来to hit the sack是指去睡觉，sack在这里是指床， hit是去床上睡觉的意思。 那我要坐下，能不能说 to hit the chair?
M: No, not really. This phrase -- to hit the sack -- has a pretty limited meaning.
L: 哟，to hit the sack只能指去睡觉，别的地方还不能用！那要是我下午想睡个午睡，能不能说：I want to hit the sack?
M: No, it's usually used to talk about going to bed at night, after a long day at work or school.
L: 午睡也不能用，只能指一天工作和学习后晚上去睡觉。那现在我已经上了一天的学，再加上晚上上了这堂枯燥无味的课，我可以说：It's time for me to hit the sack。 对不对？
M: That's correct, Li Hua. But don't forget that we have a test tomorrow.
L: 我当然不会忘掉明天的考试。
M: Ok, now go hit the sack, but after tomorrow's test we will have to study seriously for next week's test, no more goofing off.
L: 明天考试后你想好好学习，为下星期的考试作准备。没问题，我帮你准备，我们俩都会考得很好。
M: Yeah, I'm going to hit the sack. Bye, Li Hua!
Michael 今天教了李华两个常用语，一个是：to goof off，意思是做一些无聊的事，开玩笑；另一个是：to hit the sack，这是指晚上上床睡觉。
