他闻了闻牛奶，看看是否变质了。

He ___sniffed the milk to check if it was spoiled.

当我提到那个提议时，他只是轻蔑地哼了一声就走开了。

When I mentioned the proposal, he just ___sniffed dismissively and left.

这位侦探嗅出了案件中的可疑之处。

The detective ___sniffed out something suspicious in the case.