A-21：at sea 不知所措
A：I'm all at sea in Professor Black's lectures.
A: 听布莱克教授的课我是一片茫然。
B: Are you? I like his lectures.
B：真的？我喜欢听他讲的课。
A: Can you give me some suggestions?
A: 能给我提一点儿建议吗？
B: Be prepared for his lectures and then you'll feel better.
B：课前认真准备，那样你感觉会好些。
