正确答案: C

呼吸抑制

题目：吸入气中C02浓度达20%时，机体会出现（　　）

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学习资料的答案和解析：

[单选题]《长亭送别》的语言特色是

优美雅致

[单选题]How can he do so much work? He ________ stay late at the office every evening and take work home at weekends．

must

解析：考查情态动词。他能干那么多活儿，一定加班来着。表示很强的肯定推测。Need表示需要，与原句内容不符；can表示能够、能力，比较弱的可能；might表示较弱的可能；must表示较强的肯定。选项D是正确的。【句子大意】他怎么可能干那么多活儿?他肯定每晚都在办公室加班，周末还把活儿带回家去做。

[单选题]The word “deeper” in paragraph 1 is closest in meaning to which of the following?

根据以下内容，回答下面的题目。Researchers have found that REM (rapid eye movement) sleep is important to human beings．This type of sleep generally occurs four or five times during one night of sleep lasting five minutes to forty minutes for each occurrence．The deeper a person’s sleep becomes, the longer the periods of rapid eye movement．There are physical charges in the body to show that a person has changed from NREM (non-rapid eye movement) to REM sleep．Breathing becomes faster, the heart rate increases, and, as the name implies, the eyes begin to move quickly．Accompanying these physical changes in the body is a very important characteristic of REM sleep．It is during REM sleep that a person dreams．According to the passage, how often does REM sleep occur in one night?

heavier．

[单选题]_________

根据以下内容，回答下面的题目。Insure means to protect _51_ a loss of money．Most people can budget their money so that their income will cover expected expenses _52_ food, clothing, housing, and public services．But, there is no way to know _53_ who will suffer a crisis (危机) such as a serious illness, fire, flood, or a car accident．Such crises usually _54_ great expense．Even if people could predict crises, it would be hard to save enough money to _55_ the expenses．Insurance is a system _56_ a company collects money from many individuals and then pays certain expenses whenever one of those insured individuals is faced with a certain crisis．An insurance policy _57_ how much the insurance costs and how much the company will pay when a policy holder is faced with a certain crisis．There are many different kinds of insurance, _58_ hospital, motor-car and fire．Insurance can be rather expensive but most people buy insurance of some kinD．Insurance is something _59_ people buy and hope they will _60_ need．_________

by which

[单选题]函数y=x2-1和y=1-x2的图像关于（　　） (A)坐标原点对称 (B)x轴对称 (C)y轴对称 (D)直线茗+Y=0对称

[单选题]构成纤维膜后部的是 （　　）

根据以下选项，回答下面的题目：A．虹膜 B．脉络膜 C．巩膜 D．角膜 E．睫状体 构成眼球壁血管膜后部的是 （　　）

[单选题]大量饮水时引起尿量增多的主要原因是：（　　）

ADH分泌减少

[单选题]右心衰竭时所引起的组织水肿，其主要原因是（　　）

毛细血管压升高

[单选题]对尺神经的描述，错误的是 （　　）

分布于前臂大部分屈肌