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。