8. If I had known that, I ______ so.

A. wouldn’t have done                         B. didn’t do

C. won’t do                                        D. wouldn’t do

9. ______ the rain stop, the crops would be saved.

A. Will                                                B. Would

C. Should                                           D. Did

10. The police ______ a prisoner.

A. are searched for                              B. is searching

C. are searching for                                    D. is searching for

11. I cannot understand ______ to go to the meeting.

A. them to forbid                          B. them to be forbidden

C. their being forbidden                 D. their forbidding

12. X-rays are able to pass through objects and thus make ______ details that are otherwise impossible to observe.

A. it visible                                  B. visibly

C. visible                                     D. they are visible