单项选择题：生物安全柜的风机要求持续开放的时间是（） A.4小时 B.6小时 C.12小时 D.

题型：单项选择题

此题要求改正短文中的错误。如有错误则按下列情况改正：此行没有错误，在该句右边的横线上打（√）此行多一个词：把多余的词用斜线（＼）划掉，在该句右边横线上写出该词，并也用斜线划掉。此行缺一个词：在缺词处加一个漏字符号（），在该句右边的横线上写出该加的词。此行错一个词：在错的词下划一横线，在该句右边横线上写出改正后的词。

Dear friends,

It is real a good chance to have met all of you here. 1. ____________

We have spent several precious weekend in learning in the 2. _____________

English Club. Although we have been members for a short 3. _____________

period of time, we have made a great progress. That is 4. _____________

because we are all very much active and the activities are not 5. _____________

only enjoyable and also helpful. Besides, the foreign teachers 6. _____________

here work hard and try his best to make the activities 7. _____________

lively and interested. I am very pleased to say that all of 8. _____________

us greatly improved our spoken English so far. I am 9. _____________

looking forward to see all of you again in the near future! 10._____________

Thank you.

查看答案

生物安全柜的风机要求持续开放的时间是（） A.4小时 B.6小时 C.12小时 D.

问题：