7. 选B。只有插着电源的熨斗才可能引起火灾

6. 选A。下面的两个例子说明作者自己也很烦恼

5. 选D。

4. 选 A。在这些环保主义者生气之前，我已经关上了窗户。

3. 选A。

2. 选D。太忙于假装接受教育而顾不上担心科学家会把。

10. This is the necklace on which I spent all my money.

9.The man you are waiting for is a professor from Beijing University.

8. Do you remember the national park where we were attacked by a bear?

7.The person with whom I worked had to go home for a month.