问题 填空题

人体的循环系统起着运输营养和废物的作用.如图为人体血液循环示意图,其中A-D代表心脏的四腔,A为右心房,①~⑥表示血管(或血管网)请回答:

(1)血液中______细胞具有免疫作用.

(2)在①~⑥中,______属于动脉血管.

(3)用箭头、字母和序号表示出体循环途径______;血液能按照一定的方向流动.其原因是______.

(4)①代表______部的毛细血管网,请写出一项毛细血管适于物质交换的特点______.

(5)若④代表小肠内毛细血管网,用餐一段时间后,血液流经此处时发生的成分变化是______减少,______增多.

答案

(1)、血细胞有红细胞、白细胞和血小板,红细胞具有运输氧的功能,白细胞能吞噬病菌,对人体起着防御和保护的功能,血小板有止血和加速凝血的功能;血浆的主要功能是运载血细胞,运输养料和废物. 因此血液中白细胞具有免疫作用.

(2)、动脉是把血液从心脏输送到全身各处的血管,在①~⑥中,③体动脉、⑥肺动脉属于动脉血管.

(3)、血液循环分体循环和肺循环.血液循环的途径:体循环是左心室→主动脉→组织周围的毛细血管→上下腔静脉→右心房;肺循环是右心室→肺动脉→肺泡周围的毛细血管→肺静脉→左心房.因此用箭头、字母和序号表示出体循环途径D→③→④→⑤→A;血液能按照一定的方向流动.其原因是心脏和静脉内有瓣膜(有房室瓣、动脉瓣、静脉瓣).

(4)、①代表肺部的毛细血管网,毛细血管管壁最薄,只有一层上皮细胞构成,管腔最小,只允许红细胞呈单行通过,血流速度极慢,数量多,因此毛细血管适于血液与细胞之间进行物质交换.

(5)、由于小肠是消化和吸收的主要场所,所以经过小肠绒毛毛细血管的血液含养料增加,血液由含氧较多、颜色鲜红的动脉血变为含氧较少、颜色暗红的静脉血.所以若④代表小肠内毛细血管网,用餐一段时间后,血液流经此处时发生的成分变化是氧气减少,二氧化碳和营养物质增多.

故答案为:

(1)白

(2)③、⑥

(3)D→③→④→⑤→A; 有瓣膜(有房室瓣、动脉瓣、静脉瓣)

(4)肺;数量多或管壁薄或血流速度慢

(5)氧气;二氧化碳和营养物质

阅读理解

Contrary to many people believe, highly intelligent children are not necessarily certain to achieve academic success. In fact, so-called gifted students may fail to do well because they are unusually smart. Ensuring that a gifted child reaches his or her potential requires an understanding of what can go wrong and how to satisfy the unusual learning requirements of extremely bright young people.

One common problem gifted kids face is that they, and those around them, place too much importance on being smart. Such an emphasis can encourage a belief that bright people do not have to work hard to do well. Although smart kids may not need to work hard in the lower grades, when the work is easy, they may struggle and perform poorly when the work gets harder because they do not make the effort to learn. If the academic achievement of highly intelligent children remains below average for an extended period, many teachers will fail to recognize their potential. As a result, such students may not get the encouragement they need, further depressing their desire to learn. They may fall far behind in their schoolwork and even develop behavior problems.

IQ is just one element among many in the recipe for success—Children develop well or struggle in school for a host of reasons apart from IQ. These include motivation and persistence, social competence, and the support of family, educators and friends.

Because highly gifted children solve the most varied thought problems faster and more thoroughly than those with more average talents do, they need additional intellectual stimulation while they wait for the rest of the kids to learn the basics. Two central approaches are used to satisfy the educational needs of such children: acceleration and enrichment. Acceleration means studying material that is part of the standard subjects for older students. Enrichment involves learning information that falls outside the usual subjects.

A child might skip one or more grades as a way of accelerating in school. But being with older children for the entire school day—and perhaps for grade-based extracurricular activities such as sports—can make a child feel inferior in every filed outside of academics. One very bright fourth-grader who had skipped two grades remained far ahead of his classmates intellectually, but as his classmates reached adolescence, his social and other shortcomings became painfully apparent. While acceleration is not an option, or not a good one, enrichment can be. After all, school is not a race but an adventure in learning. As such, the goal is not finishing first but absorbing as much knowledge as possible in the time assigned. Thus, providing opportunities for a child to study topics outside the regular subjects can be at least as valuable as pushing him or her through the required material faster.

小题1:What is the basic reason for the low academic achievement of highly intelligent children?

A.Teachers’ failure to recognize their potential.

B.Too much emphasis on being intelligent.

C.Studying topics outside the regular subjects.

D.Lack of encouragement from teachers.小题2:According to the passage, which of the following belongs to enrichment activities for talented children?

A.Skipping one of more grades and studying together with older children.

B.Learning the same material in the standard subjects for older students.

C.Learning information that is not included in the regular subjects.

D.Learning how to read with fluency even in their pre-school days.小题3:Which of the following statements do you think is true about the writer?

A.He is in favor of enrichment rather than acceleration.

B.He is in favor of acceleration rather than enrichment.

C.He speaks highly of both enrichment and acceleration.

D.He thinks neither enrichment nor acceleration is a good choice.小题4: In this article, the writer wants to ______.

A.point out the weaknesses of acceleration for gifted children

B.compare acceleration with enrichment for gifted children

C.stress the importance of enrichment for gifted children

D.discuss how to bring out gifted children’s potential

判断题