采用单级蒸汽压缩式制冷，当蒸发温度过低时，则需要采用双级压缩_爱下问搜题

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问题多项选择题

采用单级蒸汽压缩式制冷，当蒸发温度过低时，则需要采用双级压缩式制冷循环，采用该做法的原因应是下列哪些项？（）

A、避免制冷系数降低过多

B、避免制冷剂单位质量制冷量下降过大

C、受到压缩机的排气压力与吸气压力之比数值的限制

D、避免设备的体积过大

答案

参考答案：A, B, C

填空题

选择恰当的单词填空，将答案填写在文章下面的横线上，每词限用一次（有两个是多余的）。

anyway, impossible, succeed, another, no, six, once, plan, after, ecause

     When he decided to produce his V-8 motor, Henry ford chose to make an eight-cylinder (汽缸)
engine-block in one piece. But the engineers said that was 1______.
     Ford said, "Produce it 2______."
     "But," they replied, "it is impossible."
     "Go ahead," Ford said,"and stay on the job until you 3______, no matter how much time is
required."
     Six months passed and nothing happened. Another 4______ months passed, and still nothing happened.
The engineers tried every possible 5______ to carry out (执行) the orders, but lire request (要求) seemed
impossible.
     At the end of the year, the engineers again informed Ford they had found 6______ way to carry out his
orders.
     "Go right ahead," said Ford. "I want it, and I'll have it."
    They went ahead, and then, as if by a stroke (轻触) of magic, the secret was discovered. Ford had won
7______ more!
     Henry Ford was successful 8______ one of his principles of success is that he believe what he wants.
If you can do this, you can equal (与……相当) your achievements in any calling for which you are suited.

问答题

下列词语中如有别字，请加以改正。

卑躬曲膝（）