If youth be a defect,it is one that we outgrow only too soon.

If youth be a defect,it is one that we outgrow only too soon.
If youth be a defect,it is one that we outgrow only too soon.

If youth be a defect,it is one that we outgrow only too soon.
假如青春也是一种缺憾,那就是它逝去得太快.
这是一个James Russell Lowell的经典语句.（James Russell Lowell 是十九世纪美国的一名浪漫主义诗人,评论家,编辑,和外交官.）

如果（认为）青春是个缺点，那只是因为我们长大的太快了。
个人意见

如果青春是一个缺陷，它却是我们成长太快而甩脱的东西。

如果年轻是个缺点，那也是一个我们只会太快就修正的缺点。