Experience of this kind in both the U.S. and Europe well before the Second World War.
| A．have conducted | B．have been conducted |
| C．had conducted | D．had been conducted |
Lee was faced with the of whether or not to return to his country after he got the doctor's degree in America
| A．situation | B．dilemma |
| C．environm ent | D．circumstance |
We left the small town, ______ clearly_____ no need to stay.
| A．there； being | B．it; was |
| C．it; being; | D．there；was |
There are frequently reports of accidents as fireworks ______, stored or transported.
| A．have been made | B．are being made |
| C．were made | D．have made |
Plastic bottles can be recycled but they need cleaning thoroughly, _______ they?
| A．needn't | B． don't | C．mustn't | D．can't |
Of all the methods they provided, ______ is of any help for solving the math problem.
| A．nothing | B．neither | C．none | D．no one |