1、I think he’s a kind-hearted man.（否定句）
I （don't think he is） a kind-hearted man.
2、Mother is sorry to hear that Peter failed the examination（同义句）
Mother is （sorry） to hear that Peter （didn't pass） the examination.
3、Mrs Brown likes the yellow sweater better than the black one.（改为选择疑问句）
（Which sweater does） Mrs Brown （like） better,the yellow one （or） the black one?
4、It was （windy and cold） yesterday.（就划线部分提问）
（What was） the （weather like） yesterday?
5、Why did you go there?（同义句）
（What） did you go there （for）?
6、The houses are very expensive.（改为感叹句）
How （expensive the houses are）!
7、You may clean the room until you don't have to.（连成并列句）
You may clean the room (but) you don't have to.