下列物体中，物重最接近1N的是（　　）

A．一张课桌

B．一只大鸡

C．两个鸡蛋

D．一枝铅笔

The question that puzzled us is _____ we can get rid of the air pollution in the area.

A．that how

B．how is it that

C．what is it

D．how it is that