population的谓语单复数问题over70percentofthepopulation()peasants.thatis,themajority()makingalivingbyfarming.Aare;areBis;is答案是A这两空的谓语用单还是复我都有点晕请帮我讲讲有些

　　population的谓语单复数问题

　　over70percentofthepopulation()peasants.thatis,themajority()makingalivingbyfarming.

　　Aare;areBis;is

　　答案是A这两空的谓语用单还是复我都有点晕请帮我讲讲

　　有些书说population作主语时,谓语看其表语,有的又说若被百分数修饰时,谓语用复数.究竟哪种说法是对的?第二空为什么也用复数?