怎么把这些简单句合并成定语从句

怎么把这些简单句合并成定语从句
1.The bridge that/which was built in 1959 has been rebuilt now.
2.She is going to the town that /which I do not know.
3.He told me the reason why he did not attend the meeting.
4.I missed the train that /which started at 4:50 p.m.
5.The medicine( that /which) Dr,Li gave him was quite helpful.
6.The nurse who looks after my little brother is very kind.
7.The play (that /which) we saw the night before was very interesting.
8.The plane that/which was going to tibet was late.
9.The student whose father is a worker studies very hard.
10.He is the most careful boy( who/whom) I know.
先行词作主，宾，表用关系代词that,which 作宾语时可省略。如1。2。4。5。7。8。第9题，whose 只能作定语，第三题先行词作状语，用关系副词。why，