短文改错。

     It was 9∶20 that I got to the English Corner.Some were reading some papers,and some were talking   while others were listening attentively.Someone was eager to learn from others.So I joined them in their

talk.At the first,I was afraid that my English was so good that I couldn't follow them or make myself

understood.I was also afraid someone might laugh me.But a smiled face here and an encouraging nod  

there soon put me at ease.I became bolder and came to speak English with them free.We talked about the situation at home and broad,about our school life,our hobbies and our ideas.We exchanged experiences in our studies with one another and share views,all in English.I learned a lot and made a lot of friends.

离心压缩机的密封型式有（）。

A、迷宫密封

B、机械密封

C、浮环密封

D、干气密封