问题 解答题

如图为验证人体呼出的气体中含有较多的二氧化碳的实验装置,瓶内均装入澄清的石灰水.

(1)如果气体的进出均选择弯管,在实验时,应向甲瓶______,向乙瓶______.

(2)经向两瓶内分别吹气、吸气后,石灰水明显变浑浊的是______瓶.

答案

(1)吸气时应该用乙装置原因直玻璃管是插入到石灰水中,可以让外界的空气进入石灰水,如果用甲装置则会把石灰水直接吸入到口中.因此在实验时,应向甲瓶吹气,向乙瓶吸气.

(2)人在呼吸的时候,吸入的空气中含有较多氧气,在人体内会与组织细胞内的气体进行交换,这样呼出的气体与空气相比,氧气减少,二氧化碳增多,甲装置中石灰水的浑浊程度较大,说明呼出的气体二氧化碳较多.

故答案为:

(1)吹气;吸气

(2)甲

单项选择题
单项选择题

Passage Three

Believe it or not,optical illusion can cut highway crashes.

Japan is a case in point.It has reduced automobile crashes on some roads by Rearly 75 percent using a simple optical illusion.Butst.ripes,called chevrons(人字形),painted on ther rads make drivers think that they are driving faster than they really are,and thus drivers slow down.

Now the American Automobile Association Foundation for Traffic Safety in Washington D.C. is planning t。repeat Japan’s success.Starting next year,the foundati。n will paint cheyrons and。ther pattems of stripes on selected roads around the country to test how well the patterns reduce highway erashes.

Excessive(too great)speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation.To help reduce those accidents,the foundation will conduct its tests in areas where speed-related hazards(danger)are the greatest curves,exit slopes,traffic circles,and bridges.

Some studies suggest that straight,horizontal bars painted across roads can initially cut the average speed of drivers in half.However,traffic。ften returns to full speed within months as driVers become used to seeing the painted bars.

Chevrons,scientists say,not only give drivers the impression that they are driving faster than they reallv are but als0 make a lane appear to be narrower.The result is a longer lasting reduction in highway speed and the number of traffic accidents.

On roads painted with chevrons,drivers tend to feel that().

A.thev should avoid speed.related hazards

B. they are driving in the wrong lane

C. they should slow down their speed

D. they are coming near to the speed limit