by mistake基本解释
错误地

网络释义
1. 疏忽
2. 错误地,无意地
3. 由疏忽所致
4. 错误的
5. 弄错
6. 误引

例句：
Opened colleague 's payslip by mistake ?
误开了同事的工资单？

I took your umbrella by mistake .
我错拿了你的雨伞。

But if the cops burst in by mistake it becomes a trickier issue .
但要是警察误闯了，这会是个更棘手的问题。

However by mistake I have just opened a payslip that I thought was mine but was his .
然而，我误拆开了一张工资单，我以为是我的，但却是他的。

I sort of kept them by mistake .
我留下它们是有点错误.