If it hadn't been for him, we would have gone astray.
如果不是他的话，我们就迷路了。
An error, the breadth of a single hair, can lead you a thousand li astray.
差之毫厘，谬以千里。
A lamb goes astray on a forked road.
歧路亡羊。
In the present instance, you are quite astray.
这桩事上你可完全搞错啦！
How can we sit idly by and watch him go astray?
咱们哪能眼看着他走邪道不管呢？