强调句型是英语中常用的表达方式，通过“it is/was + 被强调的部分 + that/who/whom”构成，可以强调句子中的主语、地点、时间、物品、宾语和原因等成分，使语言表达更加准确、生动有力。
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It was John who won the first prize in the competition. 强调主语，表明是约翰获得了比赛的第一名。
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It is in the library where I usually study. 强调地点，表明我通常在图书馆学习。
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It was yesterday when I realized my mistake. 强调时间，表明我是在昨天才意识到自己的错误。
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It is the new iPhone that I want to buy. 强调物品，表明我想要买的是新款iPhone。
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It was his sister whom I met at the party. 强调宾语，表明我在派对上见到的是他的妹妹。
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It is his persistence that has led to his success. 强调原因，表明他坚持不懈才导致他的成功。
