Only in this way ________ make imrrovement of the operating system.

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Unless ________ to speak, you should remain silent at the conference.

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Perhaps this book will turn out ________ to you in your studies.

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Talking to a friend over the phone, you feel that you are quite close to each other ________ the actual distance is not short.

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I wouldn't buy the TV set ________ afford it. I have already got one.

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—Sometimes students may have ________ themselves.

—Let's see what we can do to help them.

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So absorbed ________ in her work that she didn't realize I was behind her.

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Michael never dreamed of ________ for him to be sent abroad so soon.

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—Will you go to Mary's birthday party?

—No, ________ invited, I cannot. I'll be too busy then.

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The men we followed suddenly stopped and looked as if ________ whether he was going in the right direction.

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