However, at times this balance in nature is ________, resulting in a number of possibly unforeseen effects.

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—This is a project of great importance. Therefore you must direct your attention to it ________ you can.

— ________ I'm crazy about spare time hobbies, I'm most crazy about this job. ,

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In no country ________ Britain, as has been mentioned, ________ experience four seasons during the course of a single day.

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The whole building ________. But the heavy rain ________.

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A．might have burned down, would help

B．could have been burned down, helped

C．must have burned down, could help

D．should have been burned down, was helping

A computer does only what thinking people ________.

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When you go outing with your sisters, you must see to ________ that they are safe.

The two dogs ate up ________ the cake .

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He was allowed to go swimming ________ he kept near the other boys.

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It isn't cold enough for there ________ a frost tonight, so I can leave his car out quite safely.

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Mrs. Brown is so ________ about her housework that servants will not work for her.

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