问题 选择题

在人体血管中,血管壁较厚、血流速度较快的是(  )

A.动脉

B.静脉

C.毛细血管

D.淋巴管

答案

动脉的功能是把心脏的血液输送到全身各处,静脉的功能是把全身各处的血液送回心脏,毛细血管的功能是进行物质交换.因为心室收缩,血液进入动脉,压力大,故管壁最厚,血流速度最快;静脉是把全身的血液运回心脏,故管腔最大,毛细血管是进行物质交换的场所,故血流速度最慢.

 管壁管腔血流速度
动脉最厚,弹性大较小最快
静脉较厚,弹性小较大较慢
毛细血管最薄,只有一层上皮细胞构成.非常细,只允许红细胞呈单行通过非常慢
故选A

阅读理解

Answer the questions (根据短文内容回答下列问题)

1.Helen Monson has always been interested in helping her community. Her first volunteer experience was for the American Red Cross when she was in high school. When she was a school teacher, she also found time to volunteer. One year, she organized a Super Saturday Fun Day for kids in the community. She also used to volunteer at the Mint Festival every year. One summer, she served food, another year she organized an art programme.

2.After she retired, she started volunteering to help the old. When her father was older, he was not able to see as well as he used to, which made her sad because he had always enjoyed reading. She decided it would be fun to read to elderly people in her community. She also helped one woman write her stories. Ann was almost 100 years old, and Helen wrote down information about her life when she visited her. She put the information in a book and got it published. Ann was very excited to share her life story with her children and her grandchildren.

3.After a hurricane(飓风) destroyed some southern cities, Helen volunteered again for the American Red Cross. She prepared food and answered phones in a care centre. She says, “I have always liked the Red Cross because the organization helps people in need no matter what.”

4.One day, Helen read an article in the newspaper about refugees(难民) who needed to learn English. Now, she meets once a week with Sahra, a 38-year-old woman, from Somalia. Sahra is living and working in a town about 30 minutes’ walk from where Helen lives. They work on reading and writing skills. Helen gave Sahra a camera and asked her to take pictures of her daily life. She developed the pictures, and then asked Sahra questions about them. In the end, they wrote a book together and used the photos in the book. This helped Sahra learn many new words about her everyday life.

5.Helen says, “The most rewarding(有益的) part of volunteer work is becoming friends with the people I help. They enrich my life as well as I enrich theirs.”

小题1:When was Helen’s first volunteer experience for the American Red Cross?

小题2:What did Helen do after she retired?

小题3:Why was Ann excited when her book got published?

小题4:Where did Helen work when she volunteered again for the American Red Cross?

小题5:How far is Sahra living and working from Helen’s home?

小题6:Did Helen help Sahra to learn English?

小题7:What can you learn from Helen?

选择题