They are broadening the bridge to ________ the flow of traffic.
| A．put off | B．speed up | C．turn on | D．work out |
Leaves are found _______ all kinds of trees, but they differ greatly ________ size and shape.
| A．in; on | B．in; from | C．on; by | D．on; in |
To save class time, our teacher has ________ students do half of the exercises in class and complete the other half for our homework.
| A．we | B．us | C．our | D．ours |
Darwin counted 225 flowering plants, ________ he collected and brought home 193.
| A．that | B．in that | C．of which | D．all of which |
The government has taken some measures to reconstruct the earthquake-hit areas, but it must be some time ________ everything returns to normal.
| A．since | B．after | C．unless | D．before |
________ twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.
| A．Examining | B．Examined |
| C．Being examined | D．Having been examined |