________ theory，everyone must obey the rules，but ________practice，there are a few people who don’t obey the rules.
| A．In；on |
| B．On；in |
| C．In；in |
| D．On；on |
－Are you sure you have to? It’s been very late.
－I don’t know ________ I can do it if not now.
| A．how | B．what | C．when | D．that |
Is it the letter you got yesterday ________ makes you so sad?
| A．what | B．that | C．how | D．when |
It’s important to listen to your teacher carefully in class, so try not to let your mind _________.
| A．lose | B．stop | C．wander | D．disturb |
－Do you mind if I turn off the TV?－__________.
| A．Yes, please | B．No, go ahead | C．Yes, you can | D．No, I’d rather you didn’t |
Jennifer, who is my best friend, said she would go abroad for further education __________.
| A．before long | B．long before | C．shortly after | D．very fast |