What is it ? What is this? 的区别
What is it ? 单独成句，是一个疑问句。
What is this?在复杂句中作从句，是一个陈述句。
What is it then? Something\'s up, isn\'t it?
那是怎么回事呢？出问题了，是吗？
What is it? I\'m busy
什么事？我忙着呢。
What is this? This is a computer.
这个是什么？这是电脑。
What is this thing you say!
你说这是什么玩意儿！
