Some of them which remain in the air _____ the air pollution横线上填什么?cause?causes?还是causing
问题描述：
Some of them which remain in the air _____ the air pollution
横线上填什么?
cause?causes?还是causing
答
错了，应该是cause
答
cause
some of them说明复数
然后这里是谓语用一般现在时
答
cause
谓语动词