连接代词与疑问代词有什么不同

疑问代词（如what,who, which, whom等）用于引导特殊疑问句；当疑问代词用于引导名词性从句或不定式时，它就叫连接代词。比较：

Whatdo you want for your birthday?

Heasked what you wanted for your birthday.

Heasked what to wear for your birthday.