What is it that causes so many different results?

不错。强调句的特殊问句是这个样子的。但是，如果它做了宾语从句呢？还能说 What is it 吗？

我给网友提供一些强调句式的特殊问句。你在前面加上 Could you tell us 后，会是怎样？强化你的认知和记忆吧。

Could you tell us...

Who was it that found your pen in the classroom yesterday?

When was it that the Second World War broke out?

Where was it that you lost your cell phone?

How was it that he managed to get my address?

How long ago was it that you last saw her?

What was it that had made you so sad?　　

Why was it that silver was not widely used as conductor?　　

Which book is it that you want?　　

Whose umbrella was it that you took away?