4. Work hard, and you can catch up with your classmates.(改为同义句)

Work hard，             you can't catch up with your classmates.

3. They can be reused. Don't throw them away.(合并为一句）

Don't throw them away           they can be reused.

2. It is very expensive. We can't buy it.(合并为一句）

It is      expensive for us      buy.

1. It takes me10 minutes to go to school by bus.(对画线部分提问）

               it take you to go to school by bus?

5 - China is one of the first       (country)  in the world to study the science of farming.

4. It takes people 30 minutes       (go) from here to the airport.

3. This new machine's         ( advantage) is that it will produce too much pollution.

2. Biogas is not a new energy, but it is     (new).

1. It is________ (danger) to walk on the thin ice in a lake.

5. Edison wasn't a        (德国人）.He was from America.