B
When people lose legs after accidents or illnesses, emergency care and artificial limbs（假肢）often allow them to walk again. Newts （蝾螈） in the same situation, on the other hand, can grow limbs back on their own! Scientists have known for a long time that certain animals can re-grow limbs, but they haven’t quite figured out how these creatures do it.
Researchers have now come up with some new ideas. Their work may give people the ability to re-grow lost limbs. The researchers started with two simple experiments：when you cut a newt’s leg at the ankle, only the foot grows back；when you cut off a leg at the very end, the whole leg grows back. In both cases, the re-growth begins with stem cells. Stem cells can develop into nearly any type of cell in the body.
How do a newt’s stem cells know when to grow only a foot and when to re-grow a whole leg?
This question relates to another mystery. In newt’s, a cut-off leg will grow back only if the nerve bundle（神经束）in it also grows back , but if something prevents the nerve bundle from growing, the stem cells at the wound won’t re-grow a new leg.
In its study, a British team focused on a protein called n-AG. When the team prevented nerves in a limb from growing, but added the n-AG protein to stem cells in the limb, the limb still re-grew. That protein seems to guide limb re-growth. People have proteins that are similar to n-AG. Further research into these materials may someday help human limbs recover by themselves.
40. In the experiments, the researchers cut off a newt’s foot or leg to find out _____.
A. what stem cells were                     B. whether they would grow back
C. how long it would take to re-grow    D. how they would re-grow
41. A newt will re-grow its leg if _____.
A. its ankle was cut off but the nerve bundle was good
B. its leg was cut off and the nerve bundle stopped growing
C. its leg was cut off and the nerve bundle could grow back
D. its ankle and the nerve bundle were cut off
42. What do the underlined words “these materials” refer to?
A. Nerve bundles and proteins.         B. Proteins similar to n-AG.
C. Stem cells and proteins.               D. Stem cells and nerve bundles.
43. The first sentence of the passage _____.
A. acts as a lead–in                       B. shows where researchers got their new ideas
C. states the author’s opinion           D. describes the result of researchers’ studies

English was always my favorite subject. In my freshman year of high school, I could write a killer composition. In my junior year, my   1  allowed me to give spelling tests to the class. I had wonderful   2  of this year. Mrs. Alexander   3  me to sit at her desk and take over the class when she had to leave the room. Only my senior English class was   4 , as we had a teacher right out of college who expected college-level work. Every student received a “C” or “D” grade the first quarter.   5  English was still my subject.
I graduated from high school,  6  early and had children.   7  about my English, I often helped my kids with their English homework. And I   8  long articles and beautiful poetry for a newspaper. Fifteen years later, I went to college, and because I had been an “A” student, I   9  an “A” student. I lived up to my own expectations.
Yesterday, I   10  my high school report cards when I was reading old papers. That bundle (捆) of report cards   11  back the old days. I remembered sitting in my advisor’s office, explaining that I had always been excellent at English and complaining that I did not   12  a “D” from that inexperienced teacher of my senior year. The advisor was   13  but unable to change a grade.
My old   14  cards showed something else too. I wanted to tear them up or   15  them. I was not an “A” student in high school English! Somehow, I had convinced myself of this, when the grades clearly reflected an   16  student with an occasional “A” or “B”, but mostly “C”s.
Had I lived up to those   17  and define (定义) myself according to those letters, I would have never confidently   18  my writing career. Had I believed in my early grades instead of myself, I would have allowed my fear of   19  to defeat my enthusiasm and damage my creativity.   20 , I regarded my younger self as an “A” English student, except for that undeserved “D”.

When people lose legs after accidents or illnesses, emergency care and artificial limbs（假肢）often allow them to walk again. Newts （蝾螈） in the same situation, on the other hand, can grow limbs back on their own! Scientists have known for a long time that certain animals can re-grow limbs, but they haven’t quite figured out how these creatures do it.

Researchers have now come up with some new ideas. Their work may give people the ability to re-grow lost limbs. The researchers started with two simple experiments：when you cut a newt’s leg at the ankle, only the foot grows back；when you cut off a leg at the very end, the whole leg grows back. In both cases, the re-growth begins with stem cells. Stem cells can develop into nearly any type of cell in the body.

How do a newt’s stem cells know when to grow only a foot and when to re-grow a whole leg?

This question relates to another mystery. In newt’s, a cut-off leg will grow back only if the nerve bundle（神经束）in it also grows back , but if something prevents the nerve bundle from growing, the stem cells at the wound won’t re-grow a new leg.

In its study, a British team focused on a protein called n-AG. When the team prevented nerves in a limb from growing, but added the n-AG protein to stem cells in the limb, the limb still re-grew. That protein seems to guide limb re-growth. People have proteins that are similar to n-AG. Further research into these materials may someday help human limbs recover by themselves.

40. In the experiments, the researchers cut off a newt’s foot or leg to find out _____.

A. what stem cells were                    B. whether they would grow back

C. how long it would take to re-grow    D. how they would re-grow

41. A newt will re-grow its leg if _____.

A. its ankle was cut off but the nerve bundle was good

B. its leg was cut off and the nerve bundle stopped growing

C. its leg was cut off and the nerve bundle could grow back

D. its ankle and the nerve bundle were cut off

42. What do the underlined words “these materials” refer to?

A. Nerve bundles and proteins.         B. Proteins similar to n-AG.

C. Stem cells and proteins.              D. Stem cells and nerve bundles.

43. The first sentence of the passage _____.

A. acts as a lead–in                      B. shows where researchers got their new ideas

C. states the author’s opinion           D. describes the result of researchers’ studies

English was always my favorite subject. In my freshman year of high school, I could write a killer composition. In my junior year, my   1  allowed me to give spelling tests to the class. I had wonderful   2  of this year. Mrs. Alexander   3  me to sit at her desk and take over the class when she had to leave the room. Only my senior English class was   4 , as we had a teacher right out of college who expected college-level work. Every student received a “C” or “D” grade the first quarter.   5  English was still my subject.

I graduated from high school,  6  early and had children.   7  about my English, I often helped my kids with their English homework. And I   8  long articles and beautiful poetry for a newspaper. Fifteen years later, I went to college, and because I had been an “A” student, I   9  an “A” student. I lived up to my own expectations.

Yesterday, I   10  my high school report cards when I was reading old papers. That bundle (捆) of report cards   11  back the old days. I remembered sitting in my advisor’s office, explaining that I had always been excellent at English and complaining that I did not   12  a “D” from that inexperienced teacher of my senior year. The advisor was   13  but unable to change a grade.

My old   14  cards showed something else too. I wanted to tear them up or   15  them. I was not an “A” student in high school English! Somehow, I had convinced myself of this, when the grades clearly reflected an   16  student with an occasional “A” or “B”, but mostly “C”s.

Had I lived up to those   17  and define (定义) myself according to those letters, I would have never confidently   18  my writing career. Had I believed in my early grades instead of myself, I would have allowed my fear of   19  to defeat my enthusiasm and damage my creativity.   20 , I regarded my younger self as an “A” English student, except for that undeserved “D”.

1.                A．teacher         B．headmaster      C．classmate D．monitor

2.                A．memories       B．thoughts        C．expectations   D． impressions

3.                A．forced         B．appointed       C．permitted D．begged

4.                A．active          B．creative        C．interesting D． disappointing

5.                A．So             B．But            C．And D．Or

6.                A．worked         B．married         C．succeeded    D． progressed

7.                A．Confident       B．Happy          C．Sorry D． Anxious

8.                A．wrote          B．edited          C．read D． copied

9.                A．met           B．lost            C．admired  D．remained

10.               A． counted       B．remembered    C．discovered D．approached

11.               A． turned        B．brought        C．held  D． put

12.               A． deserve       B． make         C．receive   D． learn

13.               A． sympathetic    B． energetic      C．angry D． sad

14.               A． birthday       B． post          C．invitation  D． report

15.               A． keep          B． correct        C．hide  D． send

16.               A． silent         B． bright         C．average   D． outstanding

17.               A． figures        B． grades        C．papers    D． words

18.               A． changed       B． ended         C．damaged  D．sought

19.               A． change        B． risk           C． stress    D． failure

20.               A． Otherwise     B． Besides        C．Instead    D． Still

When people lose legs after accidents or illnesses, emergency care and artificial limbs（假肢）often allow them to walk again. Newts （蝾螈） in the same situation, on the other hand, can grow limbs back on their own! Scientists have known for a long time that certain animals can re-grow limbs, but they haven’t quite figured out how these creatures do it.
Researchers have now come up with some new ideas. Their work may give people the ability to re-grow lost limbs. The researchers started with two simple experiments：when you cut a newt’s leg at the ankle, only the foot grows back；when you cut off a leg at the very end, the whole leg grows back. In both cases, the re-growth begins with stem cells. Stem cells can develop into nearly any type of cell in the body.
How do a newt’s stem cells know when to grow only a foot and when to re-grow a whole leg?
This question relates to another mystery. In newt’s, a cut-off leg will grow back only if the nerve bundle（神经束）in it also grows back , but if something prevents the nerve bundle from growing, the stem cells at the wound won’t re-grow a new leg.
In its study, a British team focused on a protein called n-AG. When the team prevented nerves in a limb from growing, but added the n-AG protein to stem cells in the limb, the limb still re-grew. That protein seems to guide limb re-growth. People have proteins that are similar to n-AG. Further research into these materials may someday help human limbs recover by themselves.
40. In the experiments, the researchers cut off a newt’s foot or leg to find out _____.
A. what stem cells were                    B. whether they would grow back
C. how long it would take to re-grow    D. how they would re-grow
41. A newt will re-grow its leg if _____.
A. its ankle was cut off but the nerve bundle was good
B. its leg was cut off and the nerve bundle stopped growing
C. its leg was cut off and the nerve bundle could grow back
D. its ankle and the nerve bundle were cut off
42. What do the underlined words “these materials” refer to?
A. Nerve bundles and proteins.         B. Proteins similar to n-AG.
C. Stem cells and proteins.              D. Stem cells and nerve bundles.
43. The first sentence of the passage _____.
A. acts as a lead–in                      B. shows where researchers got their new ideas
C. states the author’s opinion           D. describes the result of researchers’ studies