She is at work on a book on the idea of charity.
她正在写一本关于慈善理念的书。
He fell upon the new idea and after a long time of hard work wrote an important paper on it.
他下苦功思考这一新观点，经过长时间的艰苦工作，写了一篇论文，对此进行阐述。
He fell upon the new idea and after a long time of hard work wrote an important paper on it.
他下苦功思考这一新观点，经过长时间的艰苦工作，写了一篇论文，对此进行阐述。
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