我正在写一位既幽默又严肃的教授，需要一些描述他的例子。可以给我三个例子吗？在描述中请对每位教授的性格特点都做简要的描述。每个例子都包含professor、humorous、serious这三个关键词。每个例子 字数在30到50字之间。至少三个句子。
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Professor Wang often starts his lectures with a humorous joke, setting a light-hearted tone, yet his serious approach to academic research is evident in his meticulous explanations. Professor Liu, known for his humorous class quizzes, reminds students of the serious consequences of academic dishonesty. Professor Chen combines humorous anecdotes with serious, in-depth discussions on ethical issues in science.
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