be doing的用法when a person is dying ,then he is living on borrowed time .什么意思啊?里面的语法讲一下is dying ,是正在走向死亡吗?he is living on borrowed time ?不是living on doing sth吗?

be doing和doing的用法区别 there be ...doing 的用法 be doing结构的用法 while doing 是一种省略主语+be的用法 那有没有when doing这种省略?请问 有be afraid doing的用法吗? be doing sth.when 可不可以用be doing,when be doing? be doing be is going to will用法的区别 be doing和be going to的区别和用法!be doing和be going to的区别和用法 各举一个be+doing+while+be+doing和be+doing+when+did的例句,be最好为过去时 be always doing 的含义和用法如题 consider to be doing 是一个怎样的用法? ashamed的用法be ashamed of +doing 还是do when的用法解释下I remember --------this used to be a quiet villageA when Bhow C where D what 英语leave的用法leave sb doing被动是不是sb be left doing? be doing的用法when a person is dying ,then he is living on borrowed time .什么意思啊?里面的语法讲一下is dying ,是正在走向死亡吗?he is living on borrowed time ?不是living on doing sth吗? being done 和 be doing ;done ；doing ; be done ;to be done 的用法 请详细点 谢谢 be busy in 的用法?它和be busy doing, be busy with有什么区别?