疑问词+动词不定式
一、定义 由两部分构成∶疑问词和动词不定式（wh-+to do）。
疑问词部分包括疑问代词who， whom， what， which和whose以及疑问副词when， where和how。此外，连接词“whether”也适用。
它主要具有以下几种功能∶
①当主语 例如∶
When to hold the meeting has not been decided. Where to camp is a problem.
②当宾语
常接在forget，find out，discuss， decide，tell， teach，know，learn， wonder，remember等动词之后作宾语 例如∶ We must know what to take notes at a meeting. He could not tell whom to talk. Do you know how to use the camera?
③当表语
例如∶ The problem is where to find the pet dog The question is who to help.
④当名词同位语
例如∶ Tom had no idea which book to choose at the bookstore. The question whether to study abroad troubled the girl.
⑤用于宾语补足语，双重宾语。 某些动词后可接”sb.+ 疑问词 + 不定式”构成的双重宾语，这类动词常用的有advise， ask， show， teach，tell等
例如∶ I can tell you where to get this kind of flower. I ask her how to improve spoken English. He will advise you what to do for the competition. Will you show me how to drive the new car?
