A．单句填空
1．It was when we were returning home________I realized what a good feeling it was to have helped someone in trouble.
答案 that [句意：当我们回家的时候，我意识到帮助了有困难的人感觉真好。when we were returning home 是一个when引导的时间状语从句，对应的主句是后面整个句子，去掉“It was”和空处，句子成立，说明该句是个强调句型，故填that。]
2．It was in this lake________
they found the long lost sword of the Ming Dynasty.
答案 that [根据句意可知，此句强调的是地点状语，考查强调句型：It is/was＋被强调部分＋that＋其它。故填that。]
3．It was the culture, rather than the language，________made it hard for him to adapt to the new environment abroad.
答案 that [句意：是文化而不是语言使他很难适应国外的新环境。根据分析可知本句为强调句。去掉It was和空格，题干可以还原为：The culture, rather than the language made it hard for him to adapt to the new environment abroad.，故填that。]
4．It's not doing the things we like, but liking the things we have to do________makes life happy.
答案 that [句意：不是做我们喜欢的事情而是去喜欢我们必须做的事情才能让人生幸福。本题考查强调句，故填that。not doing the things we like, but liking the things we have to do为被强调部分。]
5．Was it because Jack came late for school________Mr Smith got angry?
答案 that [句意：史密斯先生生气是因为杰克上学迟到吗？It is/was... that...是强调句型，故填that。本题强调的是原因状语从句。还原为普通句式为：Mr Smith got angry because Jack came late for school.。]
B．单句改错
1．It was only after he had read the papers when Mr Gross realized the task before him was extremely difficult to complete.
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答案 when→that [去掉It was和when后剩下的句子结构和意义仍然完整，为强调句型，故用that。]
2．It was not until near the end of the letter where she mentioned her own plan.
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答案 where→that [去掉It was和where后剩下的句子结构和意义仍然完整，为强调句型，故用that。]
3．It was with the help of the local guide who the mountain climber was rescued.
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答案 who→that [去掉It was和who后，剩下的句子结构和意义仍然完整，强调介词短语，故用that。]
4．It was not until I came here before I realized this place was famous for not only its beauty but also its weather.
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答案 before→that [去掉It was和before仍然是一个句子结构和意义完整的句子，为强调句，故用that。]
5．—Was it by cutting down staff where she saved the firm?
—No, it was by improving work efficiency.
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答案 where→that [去掉Was it 和where仍是一个句子结构和意义完整的句子，为强调句，故用that。]