选择填空:

This maths problem is ______ for us to work out.

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A. easy enough　　B. much easy

C. so easy　　　　D. enough easy

This problem is too difficult (困难的) for them ______.

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　　A. work out　　　　 B. work it out

The math problem is ________ difficult for me ________ work out.

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A. work out　　 B. on time    C. break down  D. go off

同义代换(选出与画线部分意思相近的词语，使句意完整。)

The maths problem is too hard to work out.

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