作业帮 > 英语 > 作业

First of all,they may have come to this planet of ours thous

来源:学生作业帮 编辑:搜搜考试网作业帮 分类:英语作业 时间:2024/08/10 00:17:45
First of all,they may have come to this planet of ours thousands or millions of years ago
为什么用现在完成式have come to,后面不是有years ago.不用过去完成式had come to
First of all,they may have come to this planet of ours thous
因为这是may have come 是情态动词的完成时 不属于现在完成时 是对过去情况作出判断的 所以 可以和过去时间连用