I don’t know _______________.
| A．how did jack think up the plan. |
| B．Jack how thought up the plan. |
| C．Jack how to think up the plan. |
| D．how Jack thought up the plan. |
Everyone should play a part_____the earth.
| A．to save | B．saved |
| C．for saving | D．in saving |
Please check your paper to ________ there are no mistakes.
| A．think of | B．try out | C．find out | D．make sure |
Liu Xi's father kept on____although he was tired.
| A．to sleep | B．sleeping | C．to work | D．working |
World Cup host Brazil would like to help China________China's soccer.
| A．improve | B．send | C．question | D．discuss |
Mrs. Green promised____all she can to help us.
| A．knowing | B．to know | C．doing | D．to do |