Before that,it was ma father or my mother who used to drop me off and pick me up on time
问题描述：
Before that,it was ma father or my mother who used to drop me off and pick me up on time
and my other sibings were already off ____by then.
A.to themselves B.by their own C.for themselves D.on their own
答
D.on their own
译文：在那以前,都是我父母准时接送我,而我的其他兄弟姐妹那时候都已经自己离开了.感觉很奇怪诶......你确定吗？没有上下文，感觉作者似乎是父母的宠儿，父母只接送他，而让其他孩子自己走。是有点奇怪的............不，我的意思是on their own这个短语是正确的吗哦，楼主问的是这个啊! on one's own= by oneself 自己（做/干事情）