自产燃料气并入瓦斯系统在（）。

A.瓦斯控制阀前

B.瓦斯控制阀后

C.瓦斯罐后

用所给动词的适当形式填空。

1. If I see him again, I ________ (tell) him what you said. 　　

2. What _________ (happen) if they don't agree with each other? 　　

3. If you give me time, I ________ (find) the solution. 　　

4. What will he say if he ever ________ (discover) the truth? 　　

5. If the train ________ (be) on time, it will be here in ten minutes.