He is satisfied with ________ his son has achieved．

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I met her ________ in a crowded bus．

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It ________ that space is limitless．

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On his way home, he found a wallet ________ on the ground．

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I'll help you, ________ I don't sleep for a night．

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The reason we are so late is ________ .

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A．because of the car breaking down

B．due to the car breaking down

C．because the car broke down

D．that the car broke down

I was about to go out ________ the bell rang．

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Someone is ringing the doorbell. Go and see ________ .

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________ made the school proud was ________ more than 90％ of the students had been admitted to key universities.

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There is a new problem involved in the popularity of private cars ________ road conditions need ________ .

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