swear

我对发生的事情一无所知，我发誓。

I don't know anything about what happened, I ___swear.

当出租车司机开始对他破口大骂时，他走开了。

When the taxi driver started to ___swear at him, he walked off.

第一次听到我的老师骂人时，我真的很震惊。

It was a real shock, the first time I heard my teacher ___swear.