The doctor will be free ____.
| A．10 minutes later | B．after ten minutes |
| C．in ten minutes | D．10 minutes after |
____ my opinion, American eat too much meat.
| A．For | B．To | C．In | D．Upon |
Steve and Jane are both very good ____ chemistry.
| A．at | B．for | C．in | D．on |
Do you often help your father ___ the farm work during the summer vacation?
| A．for | B．on | C．in | D．with |
Do you often help your father ___ the farm work during the summer vacation?
| A．for | B．on | C．in | D．with |
They sometimes go on working ____ the light of the moon.
| A．on | B．under | C．by | D．for |