6. --- I don’t know ______ I can improve my English. --- You can read some English books and magazines.
______of the water_____polluted. We must try to protect our environment.
----Pardon? I didn’t hear you just now. ---- I asked_______________________.
The stones are so heavy. How _____ they _____ to the top of the building without modern machines?
No free plastic bag in the supermarket helps to _____ white pollution.
–Would you like to food and clothes to the old at a home for the elderly with me? –Of course I would. It’s very meaningful.