97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

<strong id="rpv2t"><button id="rpv2t"></button></strong>

<pre id="rpv2t"></pre>

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

你可能感興趣的試題

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

<em id="uw2tu"></em>