问题 问答题

某同学要探究“人吸入的窄气与呼出的气体有什么不同”.

(1)他应该怎样获得两瓶呼出气体?

(2)为达到实验目的.该同学设计了以下实验.

●实验操作步骤如下:

①向盛有空气的集气瓶中滴入少量的澄清石灰水,盖上玻璃片振荡.②向盛有呼出气体的集气瓶中滴入少量的澄清石灰水.盖上玻璃片振荡.③将燃着的小木条伸入盛有空气的集气瓶.

④将燃着的小木条伸入盛有呼出气体的集气瓶.⑤对着干燥的玻璃片呼吸.

●记录实验现象如下:a.燃着的小术条火焰变小;b.澄清的石灰水无变化.c玻璃片上有小水珠生成;d.燃着的小木条火焰无变化:e.澄清的石灰水变浑浊.

●请你帮助该同学整理实验报告.找出实验操作与实验现象的对应关系(将实验现象的序号填在对应的空格上),并得出实验结论.

实验操作
实验现象
结论

答案

(1)可用排水法收集两瓶呼出气体,将集气瓶集满水,倒置在水槽中,然后通过吸管向集气瓶中呼气,排出集气瓶中的水后,用玻璃片在水下盖住瓶口后,取出集气瓶即可.

(2)我们知道,人体呼吸时能把空气中的氧气转化为二氧化碳,同时从体内带出水蒸汽,因而呼出气体中氧气的含量小于空气中氧气的含量,呼出气体中二氧化碳的含量大于空气中二氧化碳的含量,呼出气体中水蒸汽的含量大于空气中水蒸汽的含量;可根据二氧化碳能使澄清的石灰水变浑浊,用澄清的石灰水进行实验来比较二者中二氧化碳含量的多少;可根据水蒸汽遇冷凝结成小水滴,用洁净二燥的玻璃片进行实验来比较二者中水蒸汽含量的多少.

可根据二氧化碳能使澄清的石灰水变浑浊,用澄清的石灰水进行实验来比较二者中二氧化碳含量的多少,分别滴入盛有空气和呼出气体的集气瓶中,呼出的气体能使澄清的石灰水变浑浊,空气中的石灰水不变浑浊,说明呼出的气体中,二氧化碳的含量比空气中多.

可根据氧气的助燃性,用燃着的木条进行实验来比较二者中氧气含量的多少,分别将燃着的木条伸入盛有空气和呼出气体的集气瓶中,呼出的气体中燃着的小术条火焰变小,空气中燃着的小木条火焰无变化,说明呼出的气体中,氧气的含量比空气中少.

对着干燥的玻璃片呼吸,玻璃片上有小水珠生成,说明呼出的气体中水蒸气的含量比空气中的多.

故答案为;(1)将集气瓶集满水,倒置在水槽中,然后通过吸管向集气瓶中呼气,排出集气瓶中的水后,用玻璃片在水下盖住瓶口后,取出集气瓶即可;

(2)

实验操作
实验现象bedac
结论呼出气体中二氧化碳合理比空气中的含量高呼出气体中氧气的含量比空气中的含量低呼出气体中水蒸气的量比空气中的含量高

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阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项.选项中的两项为多途选项.

     Many people think of guys as being carefree when it comes to their appearance. But in fact, a lot of

guys spend plenty of time in front of the mirror. They care just as much as girls do about their body image.

     Body image is a person's opinions and feelings about his or her own body and physical appearance.    1    . You appreciate your body for its capabilities and accept its imperfections.

        2    . Here are some ideas:

     Recognize your strengths. Different body types are good for different things. What does your body

do well? Maybe your speed, strength, or coordination makes you better than others at a certain sport.

That may be basketball, table tennis, mountain biking, dancing, or even running. Or perhaps you have

non-sports skills, like drawing, painting, singing, playing a musical instrument, writing, or acting, 

          3    .

    Exercise regularly. Exercise can help you look good and feel good about yourself. Good physiques

(体形)don't just happen.     4    . A healthy habit can be as simple as exercising 20 minutes to 1 hour

three days a week. Working out can also lift your spirits.

     Respect your body! Practicing good habits - regular showering; taking care of your teeth, hair, and

skin; wearing clean clothes, and so on -can help you build a positive body image. 

    5      . Your body is just one part of who you are. Your talent for comedy, a quick wit (智慧), and all

the other things make you unique. So try not to let small imperfections take over.

A. Use this as an opportunity to discover what you're good at.

B. Be yourself.

C. Having a positive body image means feeling satisfied with the way you look.

D. Just explore talents that you feel good about.

E. They take hard work, regular workouts, and a healthy diet.

F. The good news is that self-image and body image can be changed.

G. So, what can you do to develop a positive body image?

单项选择题