In some states, the law requires that everyone have (their) car inspected at least once a year before the car can be registered.

答案是将their 改成his or her 。

请问everyone 后面一定要接单数还是可以接复数？

everyone后面的have有没有错呀？

谢谢

everyone 后面应接单数;

因为前面有require, 所以要用have