—Did the boy break the window ______?
—No. They did it when they were playing football.
| A．by accident | B．on purpose |
| C．at dusk | D．as usual |
--- He worked out such different questions at a very young age.
--- Oh, he ______ a very smart student then.
| A．could have been | B．should have been |
| C．might have been | D．must have been |
In our childhood, we were often ______ by Grandma to pay attention to our table manners.
| A．demanded | B．reminded | C．allowed | D．hoped |
Many lifestyle patterns do such _____ great harm to health that they actually speed up ____ weakening of the human body.
| A．a; 不填 | B．不填; the |
| C．a; the | D．不填；不填 |
Stay awake! You should know that it ________ to sleep in class.
| A．doesn’t permit | B．is not permitted |
| C．will not be permitted | D．was not permitted |
________ made the parents proud was________ their son had been admitted to a key university.
| A．What; because | B．What; that |
| C．That; what | D．That; because |