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【单选题】
对于齿面硬度≤350 HBS的齿轮传动,若大、小齿轮均采用45钢,一般采取的热处理A.
小齿轮淬火，大齿轮调质
B.
小齿轮淬火，大齿轮正火
C.
小齿轮调质，大齿轮正火
D.
小齿轮正火，大齿轮调质
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皮皮学刷刷变学霸
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【简答题】（8分）在一定体积的密闭容器中，进行如下化学反应： CO 2 (g)＋H 2 (g) CO(g)＋H 2 O(g)。其化学平衡常数 K 和温度 T 的关系如下表，回答下列问题： T ℃ 700 800 830 1000 1200 K 0.6 0.9 1.0 1.7 2.6 （1）该反应正向为Δ H 0；若该反应符合如图所示的关系，则在图中，Y轴是指 。 （答出一种即可） （2）能判断该反应达到化学...
【单选题】听力原文： Large modern cities are too big to control. They impose their own living conditions on the people who inhabit them. City-dwellers are obliged by their environment to adopt a wholly unnatural way...
A.
The people are not in regular communication with the rhythm of nature.
B.
The people can't enjoy sunshine and fresh air.
C.
Modern cities offer better schools, more chances of employment.
D.
Traffic fumes pollute the air.
【单选题】We sincerely trust, therefore, that the credit______ you by the time you read this letter.
A.
reaches safely
B.
has reached safely
C.
would reach safely
D.
will have safely reached
【单选题】Section B Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You shoul...
A.
developing genetically modified or nutritionally improved crops
B.
incorporating pest-resistant or virus-resistant genes into seeds of crops
C.
improving the ability of seeds to resist water shortages in certain regions
D.
identifying genes that helps neutralize aluminum toxicity in crops
【简答题】在一定体积的密闭容器中，进行如下化学反应：CO 2 (g)＋H 2 (g) CO(g)＋H 2 O(g)。其化学平衡常数K和温度T的关系如下表： T℃ 700 800 830 1000 1200 K 0.6 0.9 1.0 1.7 2.6 回答下列问题： （1）该反应正向为ΔH 0；若该反应符合下图所示的关系，则在图中，Y轴是指 。 （2）能判断该反应达到化学平衡状态的依据是 （多选扣分）。 a．...
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