草地农业生态系统

某生态系统的食物网示意图如下：

回答下列问题：

(1)在该食物网中，共有____条食物链，最高营养级属于第____营养级。

(2)乙和丙的种间关系是____。

(3)为了调查该生态系统中乙种群数量，某研究小组捕获了100只乙，经标记后放回。一段时间后，重新捕获100只，其中有10只带有标记。在该生态系统中，乙的种群数量大约为____只。

半坡原始居民比北京人进步的表现有

①会种植农作物②普遍使用磨制石器③会建造房屋④会制作陶器[ ]

A．①②③④    

B．①②③    

C．②③④    

D．①②④

第三部分：阅读理解(共20小题，每小题2，满分40分)

A

When he thought of the past,my grandfather would sometimes show us photographs of himself at school. They were brown and faded,and it was hard to believe that the blurred figure of the little boy in the short trousers and socks could ever have been Grandfather. Besides,he wore a cap---andthe boys in the photographs wore caps pulled so far forward that half of their faces were obscured. When Grandfather asked us to pick him out from the group,we would surely point to the wrong boy.

On one such occasion my younger sister,aged six,burst into tears when Grandfather proudly guided her finger to the right boy. "How could that boy be you?"she cried. "He should have a beard.” We were,of course,all convinced that grandfathers should have beards ,preferably white and bushy,like  our owngrandfather's.

"I wasa good scholar ,”Grandfather would say,wagging his beard over the photographs."I should have been top of the c1ass if I hadn't had to get up at six every morning to milk the cows and chop the wood,and again when I came home from school.”

"But Saturdays?What did you do on Saturdays?"

"Saturdays,if it was fine, I’d be out all day in the fields with the men,"replied Grandfather."And if it was wet,I’d be helping my mother with odd jobs round the house.There wasn't much time for studying."

We all tried hard to imagine what it would have been like to have been Grandfather getting up at crack of dawn and never,obviously,having amoment for himself.It seemed we had learnt something from what Grandfather had said about his childhood.

56.In the first paragraph of this passage,what theauthor really tells us is that_______.

A.his grandfather used to wear short trousers,socks and a cap as well

B.it was difficult to tell which of the boys inthe photographs was Grandfather

C.he didn't believe Grandfather wore a cap pulled forward when he was at school

D.it was fun to watch boys in the photographs wearing caps pulled forward

57. The author's sister burst into tears because________.

A.she did not get a chance to pick outGrandfather in the photographs

B.she was told which was the right boybefore she herself could pick him out

C.other children did not agree with her thatGrandfather should have had a beard

D.she found Grandfather in the photographsdid not have a beard

58.When Grandfather said,"I should have been topof the class….",he meant________.

A if he had had more time for studying,hewould have been the best in his class

B.he should have spent more time studyingrather than playing ballgames

C.his school days should not have been so hard and miserable

D.he could have never been the best studenteven if he had studied still harder

59. In the last paragraph the author said,"We all tried hard to imagine…"because________.

A. the figures of the boys in the photographswere small and blurred

B. the children had never experiencedlife like that of Grandfather

C.the photographs Grandfather showed them were brown and faded

D.Grandfather failed to tell them about his childhood in detail

获得证券资产管理业务资格的证券公司可以接受境内机构投资者的委托，进行B股的买卖。( )

景深的大小主要受（）影响。