正确答案: C

>30次／mm

题目：诊断ARDS除呼吸困难、口唇发绀外，呼吸频率应为( )

解析：C

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举一反三的答案和解析：

[单选题]According to the first paragraph an American student is allowed____．

to take a particular course in a different university

解析：参见文章第一段最后一句“It’S also possible for a student to move between one university and another during his degree course，…，”可知B正确，符合原文。

[单选题]社会基本矛盾有两对，一对是经济基础和上层建筑的矛盾，另一对是

生产力和生产关系的矛盾

[单选题]You can hardly imagine the difficulty the single mum had ______ her children.

bringing up

解析：答案为C。你很难想象单身妈妈抚养孩子的艰难。固定搭配have difficulty (in) doing sth．“做某事困难”。

[单选题]构成肋弓的肋软骨是 （ ）

第8～10肋