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问题 填空题

我国第五代隐形战机-歼20的速度达声速的2.35倍．若以680m/s的速度飞行，3秒内可飞行______m；飞行时，以______为参照物，飞行员是静止的．

答案

由v=

s
t
得：s=vt，

则飞机飞行的距离：s=vt=680m/s×3s=2040m；

飞行员始终坐在飞机里，他与飞机的位置没有发生变化，所以飞行员以飞机为参照物是静止的；

故答案为：2040；飞机．

单项选择题

The field of medicine has always attracted its share of quacks and charlatans — disreputable women and men with little or no medical knowledge who promise quick cures at cheap prices. The reasons why quackery thrives even in modern times are easy to find.To begin with, pain seems to be a chronic human condition. A person whose body or mind "hurts" will often pay any amount of money for the promise of relief. Second, even the best medical treatment cannot cure all the ills that beset men and women. People who mistrust or dislike the truths that their physicians tell them often turn to more sympathetic ears.Many people lack the training necessary to evaluate medical claims. Given the choice between (a) a reputable physician who says a cure for cancer will be long, expensive and may not work at all, and (b) a salesperson who says that several bottles of a secret formula "snake oil" will cure not only cancer but tuberculosis as well, some individuals will opt for "snake oil".Many "snake oil" remedies are highly laced with alcohol or narcotic drugs. Anyone who drinks them may get so drunk or stoned that they drown their pains in the rising tide of pleasant intoxication. Little wonder that "snake oil" is a popular cure-all for minor aches and hurts! But let there be no misunderstandings. A very few "home remedies" actually work. However, most remedies sold by quacks are not only useless, but often can be harmful as well.

According to the author, a very few home remedies are________.

A．useless

B．harmful

C．pleasant

D．effective
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单项选择题 案例分析题

男性，60岁，急性下壁、正后壁心肌梗死，突发意识丧失、抽搐，心率40次／分，心音强弱有变化，律规则，既往糖尿病、高血压多年，BP85/60mmHg。

其晕厥最可能原因为（）。

A.窦性心动过缓

B.三度房室传导阻滞

C.心源性休克

D.糖尿病酮症

E.肺梗死
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