By the time he was twelve, Edison _______ to make a living by himself.
| A．has begun | B．began | C．had begun | D．had been beginning |
Many people tried to leave the country, ________ there was much violence and a serious shortage of food supply.
| A．where | B．which |
| C．that | D．what |
Nissan's plants in Zhengzhou and Guangzhou, ________ operate in cooperation with Dongfeng Motor Corp., remained closed.
| A．which | B．who |
| C．that | D．whose |
She looked after the orphan ________ he were her own child.
| A．as if | B．even though |
| C．now that | D．in case |
The police set about arresting the suspect ________ they found enough evidence to prove him guilty.
| A．immediate | B．as long as |
| C．the moment | D．as far as |
________ scores of times, but he still couldn't understand it.
| A．Having explained |
| B．Having been explained |
| C．Though it was explained |
| D．It was explained |