He paid for a seat, when he ______ have entered free.
| A．could | B．would | C．must | D．need |
Don't try to get off the bus ____ it has stopped.
| A．while | B．as | C．since | D．before |
To understand the grammar of the sentence，you must break it______ into parts．
| A．down | B．up | C．off | D．out |
He will tell you about it ____ you get there.
| A．while | B．as | C．when | D．/ |
The classroom is big enough , but we’ll have to move if we have more students.
| A．for the moment | B．on the moment | C．in a moment | D．for a moment |
We shall go ____ you are ready.
| A．while | B．as soon as | C．as | D．since |