They have come.怎么不是came

They have come.怎么不是came They dreams have already come true 为什么是come 而不是came 后面不是说alr come,came还是have come? they---here once in the past .a,came b,have come .c has come hane come 和 have came I have come to China for three years.为什么不是I have came to Chi they walked until they come to(came to) a river they came running over翻译,为什么come 后是running he came here yesterday,为什么不是had come Have come 怎么用 I have come to this world,stark naked.不是现在完成时么?怎么不用I have ca you have just come back your hometown为什么不用came