题目内容：

We plan to reach the willage by 6:00 pm .and by then we ___for six hours
A will walk B have walked C had walled D will have walked 为什么选D

优质解答

by在...之前 by+将来时间用将来完成时 by+过去时间用过去完成时 6:00 pm 为将来某个时间 所以选D