固定结构:疑问词＋主语＋should/could/will do=疑问词＋动词不定式（to do）
1.Mr Black has bought a sofa. He wonders where to put it.
句意：布莱克先生买了一张沙发。他不知道该把它放在哪里。
原句where（疑问词） he should put=where to put 。
故改为：Mr Black has bought a sofa. He wonders where to put it.
2.Sandy is not good at history. She does not know how to improve it.
句意：桑迪不擅长历史。她不知道该如何改进。
原句how（疑问词） she could improve=how to improve。
故改为：Sandy is not good at history. She does not know how to improve it.
3.There are many toys in the shop. Peter is not sure which to buy for his cousin.
句意：商店里有许多玩具。彼得不确定该给他表弟买什么。
原句which（疑问词） he should buy=which to buy。
故改为：There are many toys in the shop. Peter is not sure which to buy for his cousin.
4.Simon loves football. He has decided what to do in the future.
句意：西蒙喜欢足球。他已经决定了将来要做什么。
原句what（疑问词） he will do=what to do。
故改为：Simon loves football. He has decided what to do in the future.
5.Wilson has ordered a robot. He wants to know when to receive it.
句意：威尔逊订购了一个机器人。他想知道什么时候能收到。
原句when（疑问词） he could reveive=when to receive。
故改为：Wilson has ordered a robot. He wants to know when to receive it.
6.Kitty is going to have a birthday party. She is thinking about who to invite.
句意：基蒂要举办一个生日聚会。她在考虑她应该邀请谁。
原句who（疑问词） she should invite=who to invite。
故改为：Kitty is going to have a birthday party. She is thinking about who to invite.
