问题 选择题

下列各项中不是小肠的结构和功能相适应特点的是(   ) 

A.小肠内壁有小肠绒毛

B.小肠中有很多消化腺,能分泌消化液

C.小肠上端与胃相通,下端与大肠相通

D.小肠绒毛壁仅有一层上皮细胞

答案

答案:C

题目分析:小肠是消化道中最长的一段,小肠内表面皱襞,皱襞上有小肠绒毛,增大了小肠消化食物和吸收营养物质的表面积;小肠内有肠液、胰液、胆汁等多种消化液,适于消化食物;小肠绒毛内有大量的毛细血管等,小肠壁、毛细血管壁都仅由一层上皮细胞构成,适于吸收营养成分。小肠上端与胃相通,下端与大肠相通,与消化和吸收没有直接关系。故选项C不符合题意。

阅读理解

Most American families are smaller than the families in other countries.Most American families have one or two parents and one or two children each.

Children in the US will leave their parents’ home when they grow up.They usually live far from their parents because they want to find good jobs.They often write to their parents or telephone them.And they often go to visit their parents on holiday.

Parents usually let their children choose their own jobs.Americans think it is important for young people to decide on their lives by themselves.

Parents ask children to do some work around their house.And in many families, parents pay their children for doing some housework so that hey learn how to make money for their own use.

小题1:The size of most American families is ____ that of other countries’.

A.larger than

B.smaller than

C.as big as

D.as small as小题2: When children grow up, they leave their parents’ home to __.

A.get married

B.be free

C.find good jobs

D.study小题3:They visit their parents ______ .

A.on weekdays

B.on weekends

C.at any time

D.on holiday小题4:Which of the following is NOT true ?

A.Children have the freedom to choose their own job.

B.Parents don’t ask their children to do the housework.

C.When children grow up, they usually live far away from their home.

D.Parents think it is important for children to make their own decision.小题5:Some parents pay their children for doing housework because _____ .

A.they want their children to learn how to make money for themselves

B.their children asked them to do so

C.they are rich

D.the law requires(要求)them to do so

填空题