1.I write to my parents (once a month)(对括号内提问）
How often do you write to your parents?
2.I thought he was ill.(改为否定句）
I didn't think he was ill.
3.I didn’t know how I could repair the bike .(变为简单句)
I didn't know how to repair the bike.
4.The room is very noisy.I can’t hear the speaker clearly.（合并成一个句子)
It is too noisy to hear the speaker clearly.