如图所示，是提起同一个物体的四种方案，如果从提高机械效率的角度来说，你认为应该选择的方案是[ ]

A.

B.

C.

D.

用place构成的短语的适当形式填空

1. Nowadays we often use plastics       wood or metal.  

2. Your remarks were a bit         .  

3. Nylon has       cotton in making some textiles(纺织品).   

4. I don't think your proposal quite           .  

5. When all the people               , the professor began his speech.