I am sure ( )people know the truth because.I have kept it a

people作“人”讲时,是集合名词,表复数概念,是可数名词.说“一个人”时,不用people.当表示两个以上的人时,可用people.如：twenty people二十个人.
people作“民族”解时,有单、复数之分.如：a people一个民族.There are 56 peoples in China.中国有56个民族.