题目内容：

by the age of 30 后面用过去完成时还是现在完成时,还是别的时态?

优质解答

by引导的时间状语只用在两个时态中：
一般将来时,例：I will get married by the age of 30.
过去完成时,例：He had had 3 kids by the age of 30.他到他30岁的时候已经有了3个孩子.言外之意是他现在已经不止30岁了.