—Have they visited the zoo many times.—______...

—Have they visited the zoo many times.

—______________.   Only once.

A. Yes, they have         B. No, they haven’t        C. No, they have

九年级英语单项填空中等难度题查看答案及解析

—_________ times have you visited Gansu Science Museum?　　 —Only once.

A.How often B.How many C.How long

九年级英语单选题简单题查看答案及解析

--I _______ the Science Museum many times so far. What about you?

--Only twice.

A.will visit B.visited C.visit D.have visited

九年级英语单选题中等难度题查看答案及解析

Many people finally succeed only after they have __________ for many times.

A.failed B.remained C.mentioned

九年级英语单选题中等难度题查看答案及解析

I　　 the Great Wall many times since 2010. It’s really amazing.

A.visit B.visited C.will visit D.have visited

九年级英语单选题中等难度题查看答案及解析

Not only Jim but also Tom and Mary 　　　　 the Great Wall since they came to China.

A. has visited　 B. have visited

C. will visit　 D. visited

九年级英语单项填空简单题查看答案及解析

The Whites _______many places of interest since they came to China.

九年级英语单项填空困难题查看答案及解析

— Families have got smaller than they were in the past.

—________. Many families only have one child today.

A.It looks really great B.It’s great fun

C.That’s true D.That’s a good idea

九年级英语单选题中等难度题查看答案及解析

—Why don’t you go to visit the Great Wall with us?

—Because I _______ there many times.

A. have been　　 B. have been to　　 C. have been in　　 D. have gone to

九年级英语单选题中等难度题查看答案及解析

Bats are the only mammals that can fly a great distance, but they have another ability. Many bats live a very long time for an animal their size.

European researchers are studying bats to understand why they live so long. They hope to make discoveries to fight the aging process (过程) in human beings.

Last week, the group of scientists said they had found important biological qualities in some bat species. The group studied bat chromosomes (染 色 体), a line of genes found in the nucleus(核) ofcells. The scientists were most interested in parts connected to the ends of the chromosomes. They are called telomeres(端 粒). Telomeres protect the ends of chromosomes, which shorten each time a cell divides. Scientists believe this shortening process causes cells to break down.　　　　　　　　 .

A report on bats was published this month in the journal Science Advances.

Among the leaders of the study was Emma Teeling, a biologist with University College Dublin in Ireland. Teeling said studying long-living mammals that have developed ways to fight aging “is another way to prove the molecular(分 子) basis of extended ‘health length.’” She added that studying bats made scientists able to learn more about the processes “that drive healthy aging.”

The European researchers studied 493 bats from four bat species. The group used information that had been gathered over more than 60 years. Of these animals, the greater mouse-eared bat generally lived the longest, an average of 37 years.

The scientists said this and a related species, which are grouped together under the name Myotis, had telomeres that did not shorten with age. Another Myotis bat holds the record for oldest age, reaching 41 years.

The scientists’ findings suggest that these bats’ cells have the ability to keep and repair their telomeres. This, they said, helps guard against the aging process. Based on its body size, a bat like the greater mouse-eared bat would be expected to live four years. But, these mammals have been found to live nearly 10 times longer than that.

The scientists found that Eighteen of these are bats. The only exception is an unusual African rodent, the naked mole rat.

1.Which sentence can be put at the end of Paragraph 3?

A. This makes scientists able to study bats.

B. That’s why bats can fly a great distance.

C. They say this is what causes aging.

D. They discover the cells connected to humans.

2.Why do some species of bats live a very long time?

A. Because they have a line of long-living genes out of the cells.

B. Because their cells have the ability to keep and repair their telomeres.

C. Because they have another ability to live longer without any food or water.

D. Because telomeres protect the ends of chromosomes to stop cells dividing.

3.The underlined word “that” refers to 　　　 .

A. four years　　 B. body size　　 C. the aging process　　 D. the ability to repair

4.What’s the best title of the passage?

A. Differences Between Long-Living Animals

B. A Science Report on Chromosomes

C. Do Bats Hold the Secret to Long Life?

D. Are Humans and Bats Similar in Protecting Themselves?

九年级英语阅读单选中等难度题查看答案及解析