at a loss 不知所措，困惑，（经营）亏本地

【例句】
However, how to work in penetrating life education has made a lot of class teachers at a loss.
可是，如何在工作中渗透生命教育却让很多班主任不知所措。

My throat was dry. I was at a loss for words.
我喉咙很干，不知说什么才好。