老师突然叫他回答问题,他一下子不知所措。Lǎoshī tūrán jiào tā huídá wèntí, tā yíxiàzi bùzhīsuǒcuò.The teacher suddenly called on him to answer a question, and he was completely at a loss.
第一次上台,她紧张得不知所措。Dì yí cì shàng tái, tā jǐnzhāng de bùzhīsuǒcuò.On stage for the first time, she was so nervous she did not know what to do.
迷路以后,孩子站在路口不知所措。Mílù yǐhòu, háizi zhàn zài lùkǒu bùzhīsuǒcuò.After getting lost, the child stood at the intersection at a loss.