"动极者镇之以静"所说明的阴阳关系是（） A.阴阳相互转化 B.阴阳互根互用 C.阴

双侧肺大泡破裂患者人工通气时，气道压力不应超过20cmH₂0。

物业管理法律责任的主要特点包括（）。

A.法律责任的承担主体具有特定的身份

B.技术规范确定的责任分量比较大

C.法定责任与协议责任相结合

D.违法行为与损害结果之间存在着必然性

E.法律责任的种类和复合关系复杂性

有一实用氧气钢瓶，瓶内氧气的压强P=5.0×10³Pa，温度t=27℃，求氧气的密度，氧的摩尔质量μ=3.2×10²kg/mol，结果取两位数字．

阅读理解。

     In many cultures white is often associated with something positive. A white-collar job, for instance,

is the kind of job many people look for, working with your brain and not your hands.

     White has a clean and pure image.That is why doctors, dentists, and nurses usually wear white

uniforms. Babies are dressed in white at baptisms (洗礼) and brides wear white wedding gowns at

weddings.White in these cases is the symbol of innocence or purity.

     Sometimes white is used in expressions that are not good. "Whitewash" is one such expression.At

first, "whitewash" meant to paint over something with white paint to make it look better. However, it

means something different today: to hide or to cover up mistakes or failures.

     A "white elephant" is another example of white used in a negative way. In ancient Thailand, a white

elephant was regarded as a sacred animal, but it was very expensive to keep. The kings of those days

presented a white elephant to the people they wanted to ruin.Once they received this holy, royal animal

      as a gift, they were not allowed to sell or kill it.Today, a "white elephant" means something that is

big, useless, and unwanted. In America, when people want to get rid of their furniture or clothes, they

often have a "white elephant sale".

1. The text is mainly about _____.

A. the meanings of white in English culture

B. the history of some English idioms

C. some interesting customs in English culture

D. some useful English words and expressions

2. Which expression has an historical background?

A. White-wash.

B. White-collar.

C. White elephant.

D. White elephant sale.

3. In which statement does"white" have a negative meaning?

A. A boy is dressed in white at baptisms.

B. A bride wears a white wedding gown.

C. A man whitewashes his crime.

D. A girl finds a white collar job.

4. The author develops the text mainly by ______.

A. analyzing its cause and effect

B. providing typical examples

C. comparing different ideas

D. following the time order

差压式流量计的应用范围很广。