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單項選擇題

The ratio of the work done by the machine（）the work done on it is called the efficiency of the machine.

A.against
B.with
C.to
D.for

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單項選擇題

His inability to learn foreign languages was a(n（）to his career.

A.objection
B.defect
C.obstacle
D.depression

單項選擇題

In general , the amount that a student spends for housing should be held to one-fifth the total（）for living expenses.

A.acceptable
B.available
C.advisable
D.applicable