用括号里所给词的适当形式填。每空一词。
When did your sister get _________(marry)?
Air _________（pollute）has become a serious problem.
The song “Memory” has been popular since the_________(twenty) century.
It’s _________(bore) to see the same channel.
Our classroom is at the _________(south) end of our school.
Bob loves water sports, such as swimming and _________(sail).