细读句子，用所给词的适当形式填空。

Armstrong landed on the moon ________(success)．

细读句子，用所给词的适当形式填空。

It is ________(good)________(safe)than sorry．

细读句子，用所给词的适当形式填空。

We are happy to know that both of us have been selected ________(be)the voluntary workers for the Olympic Games in Beijing in 2008．

细读句子，用所给词的适当形式填空。

－When did you became ________(interest)in ________(ski)?

－When I was only five years old．

细读句子，用所给词的适当形式填空。

－Is Neil Armstrong the first man ________(walk)on the moon?

－Of course he is．

动脑筋想一想，下面的空应该怎么填？

It is believed that the Great Wall was built for ________(protect)the northern border of China．

动脑筋想一想，下面的空应该怎么填？

My cousin used to ________(ride)to school, but now she is used to ________(walk)to school．

动脑筋想一想，下面的空应该怎么填？

I would like ________(travel)around the world when I grow up．

动脑筋想一想，下面的空应该怎么填？

Is it important and necessary for us teenagers ________(do)much extra exercises after school every day?

动脑筋想一想，下面的空应该怎么填？

People are encouraged ________(cycle)to work because it produces no pollution．