How can school ban mobile phones completely __________ some of the parents simply don’t follow the rule?
| A．unless | B．when | C．until | D．before |
Helen ______ her keys in the office so she had to wait until her husband ______ home.
| A．has left; comes | B．left; had come |
| C．had left; came | D．had left; would come |
The teacher, with 6 girls and 8 boys of her class, ______ visiting a museum when the earthquake struck.
| A．would be | B．were | C．had been | D．was |
With a lot of difficult problems ______, the newly-elected president is having a hard time.
| A．settled | B．settling | C．to settle | D．being settled |
—I must apologize for ______ ahead of time.
—That’s all right.
| A．not letting you to know | B．not letting you know |
| C．letting you know not | D．letting not you know |
------ I missed the bus. What a pity !
------______. There will be another one in five minutes.
| A．Never mind | B．Not at all | C．Take your time | D．No hurry |