2. It is _____ this arable land that the farmers produce food_____ the whole population of China.

1. Scientists started to develop new techniques to increase agricultural production ________ harming the environment.

10. Some waste may be thrown into the sea, while others may be dumped more than 40 km from living places. What to do with the waste_______________ the nature of the materials.

9. The Robinsons have always ____________________________ their neighbors.

8. I soon found that the work I was doing had been done by someone else. __________________, I was wasting my time.

7. In old Egypt kings ____________ pyramids _________the symbol of their power.

6. The inventions of many electric appliances (电器)________________ people's life.

5. He drove in the wrong lane, but the police _______him _______ as they were busy with the accident nearby.

4. The boy was late. He tried to enter the classroom without being noticed by the teacher, but luck ____________ him. The head teacher was standing at the door.

3. The girl _______________ her father ______ not letting her know the news earlier.