Nearly 50% of the Irap population,which is over 20 million,is under 15 years old.

问题描述:

Nearly 50% of the Irap population,which is over 20 million,is under 15 years old.
请说明20 million是指Nearly 50% of the Irap population,还是the Irap population的全部.
那the only one of the people houweishenme用is?

是指Nearly 50% of the Irap population.从后面的意思可以看出来,因为不可能所有伊拉克人都小于15岁.之所以用is是因为which所指代的是一个数字,而非许多人