A：I've got to go home and study.我必须回家读书。
B：For what?为什么?
A：The test tomorrow.为明天的考试啊!
B：If you don't know it by now, you might as well not bother studying.如果你到现在对考试材料还没有弄懂的话，你倒不如不用麻烦去学了。