Help others whenever you can _______ youwill make the world a nicer place to live in

I get into the habit of surfing the Internet___I can find a lot of useful information

If you want to do the experiment again, you’d better be more careful _____ you made a mistake. [ ]

ore and more important to protectour earth.—-I think so. If everyone ______acontribution to it, our world will be more beautifu..

China is larger than ____ in Asia (亚洲) and larger than ___ in Africa(非洲).