It is thought that one billion people I the world,  _   is half the word’s workers, earn their living by farming.

A．if

B．that

C．which

D．what

我国曾经对三年期以上的国债进行保值贴补，这是对（）的补偿。

A．信用风险 

B．利率风险 

C．政策风险 

D．购买力风险