My mother is always warning me when I go out, “Don’t get off the bus ____it is stopping.”
| A．until | B．before | C．while | D．After |
Her pronunciation is as good as, if ____than, her teacher's.
| A．no better | B．not better | C．no good | D．not good |
In that month, he earned as much as, if ____ than, $40 000.
| A．no more | B．not more | C．no much | D．not much |
The research is so designed that once _____ nothing can be done to change it.
| A．begins | B．having begun | C．beginning | D．begun |
If _____ carefully, the experiment will be successful.
| A．do | B．does | C．done | D．doing |
He is a man of few words, and seldom speaks until _____ to.
| A．spoken | B．speaking | C．speak | D．be spoken |