具体语境是啥
字面意思我认为是知道从左手到右手里的东西
找了段文章
Do you know your right hand from your left?Of course you do – but a surprisingly large number of doctors don’t.This can be a problem if you’re amputating a leg.
Sometimes they get the right and left bit sorted out, but still carry out the wrong procedure on the patient, or they get the procedure right, but on a patient who should never had it in the first place.
这里的意思就是说你知道你在做什么吗?你当然知道——但是让人吃惊的是大多数的医生并不知道自己再做什么,如果你要做截肢手术的话这就成为了一个大麻烦.