问题 单项选择题

TSP采样法属于( )。

A.填充柱阻留法
B.直接采样法
C.滤料阻留法
D.自然积集法

答案

参考答案:C

解析: TSP的测定原理:用抽气动力抽取一定体积的空气通过恒重的滤膜,则空气中的悬浮颗粒物被阻留滤膜上,根据采样前后滤膜质量之差及采样体积,即可算出TSP的质量浓度。
滤料阻留法:将过滤材料(滤纸、滤膜等)放在采样夹上,用抽气装置抽气,则空气中的颗粒物被阻留在过滤材料上,称量过滤材料上富集的颗粒物质量,根据采样体积,即可计算出空气中颗粒物的浓度。所以C正确。

阅读理解

Many of us believe that a person’s mind becomes less active as he grows older. But this is not true, according to Dr Jarvik, professor of psychiatry at the University of California. She has studied the mental functioning of aging persons for several years. For example, one of her studies concerns 136 pairs of twins (双胞胎), who were first examined when they were already 60 years old. As Dr Jarvik continued the study of the twins into their 70s and 80s, their minds did not generally decline (衰弱) as was expected.

  However, there was some decline in their psycho-motor speed. This means that it took them longer to finish mental tasks than it used to. But when speed was not a factor, they lost very little intellectual (智力的) ability over the years. In general, Dr Jarvik’s studies have shown that there is no decline in knowledge or reasoning ability. This is true not only with those in their 30s and 40s, but with those in their 60s and 70s as well.

  It is true that older people themselves often complain that their memory is not as good as it once was. However, much of what we call “loss of memory” is not that at all. There usually was incomplete learning in the first place. For example, the older person perhaps had trouble hearing, or poor vision, or was trying to learn the new thing at too fast a speed. In the cases where the older person’s mind really seems to get worse, it is not necessarily a sign of decline due to old age. Often it is simply a sign of a sad emotional state. 

小题1: This passage is mainly about _______.

A.what caused mental decline

B.a new discovery about mental decline

C.the difference between middle-aged and older persons

D.how Dr Jarvik studied mental functioning of the twins小题2:The word “psychiatry” in paragraph 1 most probably means _______.

A.the study of diseases of the mind

B.the study of physical diseases

C.the study of twins’ growth

D.the study of human behavior小题3:More often than not, what we call mental decline is actually a sign of _______.

A.a worsening state of health

B.old age

C.nervous tension

D.a state of unhappiness

单项选择题