1£®The reason ________ she changed her mind is quite clear.

2£®The days ________ they travelled together meant a lot to him.

3£®I saw a house, the windows of ________ were broken.

4£®She has two sons, both of ________ graduated from Harvard University.

5£®Nobody knows the reason for ________ she didn't attend the meeting.

6£®We went through a period ________ communications were very difficult in the rural areas.

7£®The children, all of ________ had played the whole day long, were worn out.

8£®We visited the car factory ________ my uncle once worked three years ago.

9£®This is the factory ________ I visited last year.

10£®The old man has two sons, and both of ________ are lawyers.