When was it ________you met him in the library？

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It was in the lab ________was taken charge of by professor Black ________they did the experiment．

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It was ________that caused him to serve dinner an hour later than usual．

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Was it because it snowed last night ________you didn't come？

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It was the training that he had as a young man ________led to his success．

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It was for this reason ________her uncle moved out of New York and settled down in a small village．

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________ is ________who wants to see you．

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The Parkers bought a new house but ________will need a lot of work before they can move in．

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It was 600 years ago ________the first clock with a face and an hour hand made．

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Was it during the Second World War ________he died？

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