I was about to leave _____ the telephone rang.
| A．after | B．while | C．when | D．before |
The engine just won't start.Something seems ________ wrong with it.
| A．to go | B．to have gone |
| C．going | D．having gone |
It's no use ________ without taking any action.
| A．complain | B．complaining |
| C．being complained | D．to be complained |
No matter how bright a talker you are, there are times when it's better ________ silent.
| A．remain | B．be remaining |
| C．having remained | D．to remain |
________basic firstaid techniques will help you respond quickly to emergencies.
| A．Known | B．Having known |
| C．Knowing | D．Being known |
If he takes on this work, he will have no choice but ________ an even greater challenge.
| A．meets | B．meeting |
| C．meet | D．to meet |