Everyone listened attentively to the professor's lecture.
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This idiom originates from the legend of Xu You (许由), an ancient hermit. When Emperor Yao offered him the throne, he was so offended that he went to wash his ears in a stream, as if the words had dirtied them.
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This is a formal and polite expression. Using it shows respect toward the speaker. It's common in business meetings and formal conversations.
