31. We______ on the project for three hours. Let’s have a rest.
| A．are working | B．have been working | C．worked | D．had worked |
It is good to ________, for people will always believe in you．
| A．keep your word | B．hold your breath |
| C．take a chance | D．play jokes |
Nobody knows ________ to visit our school ．
| A．when will he come | B．when does he come |
| C．when he will come | D．when he does come |
I am feeling sick now．I ________ so much chocolate．
| A．needn’t have eaten | B．couldn’t have eaten |
| C．mustn’t have eaten | D．shouldn’ t have eaten |
Many people have come to realize they should go on ________ diet and make room for ________ exercise．
| A．a; 不填 | B．the; an | C．the; the | D．不填; an |
Americans spend more money than they have by using credit cards, so they are always .
| A．in peace | B．in danger | C．in relief | D．in debt |