按要求写句子。

1. That blue sweater is twelve dollars.(对画线部分提问)

_______ _______ is that blue sweater?

2. Can I help you?(改为同义句)

_______ can I _______ for you?

3. Tim's T-shirt is white.(对画线部分提问)

_______ _______ is Tim's T-shirt?

4．The shoes are black.(改为同义句)

They are_______ _______ .

5．I like the red skirt.(改为一般疑问句)

_______ _______ _______ the red skirt?

压缩机入口前必须设置气液分离器，以防止管道内冷凝带入压缩机。