The valley was so deep that it had been ten seconds _________the stone feel off to the bottom.
A since B before C when D until
—Who is the girl standing over there?
—Well, if you ________ know, her name is Mabel.
| A．may |
| B．can |
| C．must |
| D．shall |
You and I could hardly work together,________?
| A．could you |
| B．couldn’t I |
| C．couldn’t we |
| D．could we |
—It’s the office! So you ________ know eating is not allowed here.
—Oh, sorry.
| A．must |
| B．will |
| C．may |
| D．need |
What do you mean, there are only ten tickets? There ________ be twelve.
| A．should |
| B．would |
| C．will |
| D．shall |
One of the few things you ________ say about English people with certainty is that they talk a lot about the weather.
| A．need |
| B．must |
| C．should |
| D．can |