1,you mustn't be late if you want___________(赶上早班公共汽车)
2,I'll tell him about it when______________(他来看我)
3,don't talk to me when i'm doing____________(作业)
4,you must read it again before you__________(做这道练习题)
5,he must be very tired after he walked_________(3小时)
6,you need help if you can't___________(修理这台电视机)
7,they go to the farm to help with the rice harvest when the farmers______(很忙)