The little boy is dirty from head to foot because he ___ in the mud all morning.
| A．has played | B．is playing | C．has been playing | D．was playing |
Someone called me up in the middle of the night, but they hung up ________I could answer the phone.
| A．since | B．until | C．before | D．as |
The child asked his mother go out to play tennis.
| A．that he could | B．if he could | C．whether could he | D．that if he could |
Good use that the villagers have been ________ the water resources has brought them a large income.
| A．making of | B．putting into | C．taking on | D．providing with |
There was a lot of fun at yesterday's party. You ________ come，and what a pity!
| A．might have | B．should have | C．could have | D．would have |
My hometown has changed so much that I can't ________ it.
| A．know | B．understand | C．recognize | D．realize |