完整的说明离心力的计算与哪些因素相关？（） A.离心机品牌 B.台式或落地式 C.塔

食管癌肿侵入主动脉，溃烂破裂，可引起（）。

A．声音嘶哑

B．大量呕血

C．食管气管瘘

D．呛咳及肺部感染

E．食物反流

Passage OneA recent study indicates that the “short sleepers” had been more or less average in their sleep needs until the men were in their teens. But at about age 15 or so, the men voluntarily began cutting down their nightly sleep time because of pressures from school, work, and other activities. These men tended to view their nightly periods of unconsciousness as bothersome interruptions in their daily routines.In general, these “short sleepers” appeared ambitious, active, energetic, cheerful, conformist in their opinions, and very sure about their career choices. They often held several jobs at once, or work fullor parttime while going to school. And many of them had a p urge to appear “normal” or “acceptable” to their friends and associates.When asked to recall their dreams, the “short sleepers” did poorly. More than this, they seemed to prefer not remembering. In similar fashion, their usual way of dealing with psychological problems was to deny that the problem existed, and then to keep busy in the hope that the trouble would go away.The sleep patterns of the “short sleepers” were similar to, but less extreme than, sleep patterns shown by many mental patients categorized as manic.The “long sleepers” were quite different indeed. According to the study, these young men had lengthy sleeps since childhood. They seemed to enjoy their sleep, protected it, and were quite concerned when they were occasionally deprived of their desired 9 hours of nightly bed rest. They tended to recall their dreams much better than did the “short sleepers”.Many of the “long sleepers” were shy, anxious, introverted, inhibited, passive, mildly depressed, and unsure of themselves (particularly in social situations). Several openly state that sleep was an escape from their daily problems.

When sometimes they cannot enjoy adequate sleep, the long sleepers might ().

A．appear disturbed

B．become energetic

C．feel dissatisfied

D．be extremely depressed

体积管检定系统,标准量器直接与大气相通,高速液流难免夹带空气进入计量检定系统

急性胃炎的表现为（）

A．进行性咽下困难

B．慢性、周期性、节律性上腹疼痛

C．大量呕吐隔夜食物

D．进食污染食物后急性呕吐，上腹不适伴腹痛

E．右下腹痛，常在进食后诱发，大便后缓解

不适当地校装升降舵配平调整片系统，将影响飞机绕什么轴的平衡？（）

A、横轴。

B、纵轴。

C、立轴。

D、偏航力矩。