1. Forests can __________ the water __________ (防止) washing the earth away.
2. I hope you can __________ me __________ (提供) some information about Fujian.
3. Don't forget to __________ __________ (关掉) lights before you leave the room.
4. We __________ __________ (应该) to plant some trees in our new school evey year.
5. __________ __________ (到目前为止), our government has taken many measures to control the
    population.