2020年宁夏专升本大学英语真题

55. What does the passage try to tell us?

A. Do more at school

B. Care for others

C. Use the Internet properly.

D. All of the above

Passage Four

How does an ecosystem(生态系统)work? What makes the populations of dfferent species the way they are? Why are there so many flies and so few wolves? To find an answer scientists have built mathematical models of food webs,noting who eats whom and how much each one eats.

54 With such models, scientists have found out some key principles operating in food webs.Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator{掠食动物) always eats huge numbers of a single prey猎物)，the two specdes are strongly linked; when a predator lves on various species, they are weakly inked. Food webs may be dominated by many weak links because that arangement is more stable over the long term. Ifa predator can eat several species, it can sunve the exintion(灭绝of one of them.And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch llows the original prey to recover.The weak links may thus keep species from driving one another to extinction.

ss Mathematical models have also revealed that food webs may be unstable, where small shanes of top Dredators can lead to bi efectes thouhbour entire ecoystems in the 19605，scientists proposed that predators at the top of a food web had a srprising amount of control over the size of populations of other species including species they did not directly ttack.And unplanned human actvities have proved the idea of top down control by top predators to be true. In the ocean, we fished for top predators such as cod on an industrial scale, while on land,we klled off large predators such as wolves. These actions have greatly afetede the ecologial balance.

Scientists have built an early warning system based on mathematical models. Ideally the system would tell us when to adapt human atvites that are pushing an ecosystem toward a breakdown or would even alow us to pull an ecosystem back from the borderine. Prevention is key, scientits say, because once ecoystems pass their tpping point(临界点),it is remarkably difficult for them to return.

56. What have scients discovered with the help of mathematial models of food webs?

A. The living habits of species in food web.

B. The rules governing food webs of the ecosystems.

C. The approaches to studying the species in the ecosystems.

D. The differences between weak and strong links in food webs.

57. A strong link is found between two species when a predator___

A. has a wide food choice

B. can easilty find new prey

C sticks to one prey species

D can quickly move to another place

58. What will happen if the populations of top predators in a food web greaty decline?

A. The prey species they directly attack will die out.

B. The species they indirectly atack will turn into top predators

C. The living environment of other species will remain unchanged.

D The populations of other species will experience unexpected changes

59. What concusion can be drawn from the examples in Paragraph4?

A Uncortolled human actvities greatly upset ecosystems

B Rapid economic development threatens animal habitats

c. Species of commercial value dominate other species

D. Industrial activitles help keep food webs stable.

60. HOW does an early waming system help us maintain the eologia blan?

A. By gtting ilal practices under control.

B. By soppinp us from klingg large predators.

C.By binging the broken down ecsystems back to normal.

D. By sgnaling the urgent need for taking preventve action.

Part m Cloxe Test(20 polints. 3point each)

Directions: There are 20 blanks in eacth of the tllowing twO passage four choices marked A, B, C and D. You should choose the ONE that best fits Into the Passage. Then write the corresponding ltter on the Answer Sheet.

Section A(非英语专业考生作答61-80选项，并在答题卡相应区域填涂。)

I was ready to pay for my bananas at the grocerv one night, when fear seized me. My wallet was gone. Icould only have left it on the G9 bus, which was now seeding in the dark to some 61 station.

The 62 moment was quicky flowed by mental math, how much time and money would it cost to replace the 63 of that ltle wlle? The credit cards, the driver's lcense. the cash, all lost to the bus.

Two hours later, back at my house, 1 heard a knock on the door. My husband 64 it while 1 was on the phone in the dining room. "Does Jennifer live here? "I heard a lady say. In my husband's hand was my wallet, with not a penny, 65 She left before 1 could 66 make it to the door to offer my thanks.

After sharing the story online, Iheard from someone, who 67 the lady as Erin Smith.Without 68. clld to thank her. She said she 69 my wallet on a bus seat. She 70 that going to a stranger's house was a 71 move, but she decided to take the chance.“If I were in that 72 ,1 would want someone to try to find me, "she said.

This one stranger responded beautifully to my small 73 but she actually wasn't the only one. Right after Erin 74 my wallet on the bus, she posted a picture of my drlver's license to an online forum(论坛), trying to see 75 anyone knew me. No sooner dlid she leave my doorstep than I had emails from two women whose kids go to my son's nursery and who recognized my face. I've never 76 words with those moms beyond small talk, but they wanted to help,1 read that people are more divided than ever, but that's not how the people 177 tend to act.

78, I feel blessed someone had wanted to help a stranger. Erin had gone 79 what almostanyone would have done, finding my house on a bitetly cold night, and for that | was extremely 80

61. A. acessible

B. hidden

C unknown

D. comvenient

62. A. face saving

B. brain-washing

C. eye-catching

D. heart stopping

63. A. parts

B. contents

C. details

D. ingredients

64. A. ignored

B. answered

C. examine

D. interrupted

65. A. missing

B. returmed

C. remaining

D. abandoned

66. A. sill

B. ever

C. yet

D. even

67. A. selected

B. appointed

C. identified

D. defined

68. A. delay

B.alarm

C regret

D. invitation

69. A. moved

B. placed

C opened

D. found

70. A. disagreed

B. complained

C. calculated

D. recommended

71 A slless

B.risky

C slow

D. personal

72. A. site

B. direction

C situation

　　感谢您阅读2020年宁夏专升本大学英语真题，本文出自：诚为径统招专升本网，转载需带上本文链接地址：https://tzzsb.cwjedu.com/lnzt/37443/p3