31. ----Who are you waiting for?
---__________ the man wounded in the left leg.
| A．The doctor will operate on | B．The nurse to be looked after |
| C．The doctor to operate on | D．His brother got |
______ life began on earth is one of the biggest puzzles that scientist found hard ______.
| A．How; solving | B．When; to be solved |
| C．How; to solve | D．Which; to solve |
President Obama held talks with Chinese President Hu Jintao in Beijing, ________ economic recovery, climate change and stopping the spread of nuclear weapons.
| A．which was discussed | B．in which they-discussed |
| C．when they discussed | D．which discussed |
The government has taken some measures to solve the shortage of electricity, but it may be some time ________ we have enough power.
| A．since | B．after | C．unless | D．before |
A small plane crashed into a hillside five miles east of the city, ________ all four people on board.
| A．killed | B．killing | C．kills | D．to kill |
At first, his teacher couldn’t’ realize that Lang Lang had a ________ for music though he said he wanted to learn the piano so much.
| A．knowledge | B．present | C．gift | D．desire |