问题 选择题

下列叙述中,属于人体毛细血管特点的是(  )

A.内径小,血流速度快,便于物质交换

B.管壁厚,破损时血液喷射而出

C.内表面通常具有防止血液倒流的静脉瓣

D.内径小,只允许红细胞单行通过,血流速度慢,便于进行物质交换

答案

A、毛细血管中血流速度很慢,故A说法错误;

B、毛细血管的管壁很薄,只有一层上皮细胞构成,故B说法错误;

C、静脉瓣存在在四肢的静脉内,毛细血管中没有静脉瓣,故C说法错误;

D、毛细血管具有内径小,只允许红细胞单行通过,血流速度慢,便于进行物质交换,故D正确;

故选:D

阅读理解

Children today would rather read, do housework or even do homework than play outside--- and they get out half as much as their parents did when they were young.

According to a UK study, those growing up during the 1970s and 1980s enjoying more than two hours of outdoor activities each weekday, and nine hours on weekends—whatever the weather is. But their children play outside for just over one hour each weekday, and fewer than five hours on Saturdays and Sundays.

So, the UK started an activity to encourage children to give up 30 minutes of screen time a day to play outdoors.

The Wild Network, born on September 25, 2013, is joined by more than 300 organizations, large or small. It tries to attract children away from television and computer screen and into woods and parks.

It is the biggest ever activity to reconnect children with nature and outdoor activities, and it plans to help improve children’s health.

Suggestions on how to get more time in nature including collecting fruits, camping, watching autumn colour on trees and so on.

This is not the first time the message of less screen, more play has been brought up. Children in the 1980s were encouraged to do the same by BBC TV show Why Don’t You, which encouraged children to “turn off your TV set, and go to do something less boring instead”.

You can learn more about the activity by visiting Http://www. Projectwildthing.com.

小题1: We can learn from the second paragraph that _______.

A.today’s children have more free time

B.today’s children spend more time outdoors

C.the parents had more free time when they were young

D.The parents spent more time outdoors when they were young小题2:The Wild Network was started to __________.

A.encourage children to spend more time outdoors

B.encourage children to play with their parents outdoors

C.encourage children to spend more time on their studies

D.encourage parents to spend more time with their children小题3:What can we learn about the Wild Network?

A.It was set up this year

B.It was the best ever activity

C.Both large organizations or small can join it

D.You can learn about it from the show Why Don’t You小题4: Which of the following activities is not mentioned?

A.Camping

B.Collecting fruits

C.Bird watching

D.Autumn clour watching小题5:The underlined part “do the same” can be replaced by _______.

A.start an activity

B.play outdoors

C.do homework

D.do housework

单项选择题 B型题