Scientists also have no idea how long it will be before all wild animals in the cages _____.
| A．should be set free | B．will be set free | C．are set free | D．would be set free |
____ I saw him, I knew he was the man the police were looking for.
| A．Previously | B．Instantly |
| C．Accurately | D．Especially |
Most of the taxi-drivers say what they earn every day actually can hardly ____ the cost of their life.
| A．cover | B．afford | C．include | D．contain |
—Look! What are the Browns busy with?
—Well, Mrs Brown is cutting the grass; ____, her husband is planting the roses.
| A．rather | B．instead | C．thus | D．meanwhile |
As we know, fresh air and proper amounts of exercise can____ good health.
| A．link to | B．contribute to |
| C．depend on | D．concentrate on |
The computer system____ suddenly while he was searching for information on the Internet.
| A．broke out | B．broke in |
| C．broke up | D．broke down |