难题
word A1- difficult problem
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答案显然是否定的，因为在那些解开世界级难题的瞬间，我曾真切地感受到了思维跳跃的纯粹快乐。
他不仅为学生解答了学业上的难题，更将他们视为自己最骄傲的传人。
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