[单项选择]After years of research, scientists have ______the virus that is responsible for the disease.
A. recognized
B. identified
C. guaranteed
D. notified

[单项选择]After years of research, scientists have ______the virus that is responsible for the disease.


A. recognized
B. identified
C. guaranteed
D. notified

[单项选择]After years of research, scientists have ______ the virus that is responsible for the disease.
A. recognized
B. identified
C. guaranteed
D. notified

[单项选择]Scientists have spent years into the effects of certain chemicals on the human brain, but with no result.（）
A. studying
B. researching
C. investigating
D. inspecting

[单项选择]Scientists have spent years_________ into the effects of certain chemicals on the human brain with no results.
A. studying
B. investigating
C. researching
D. inspecting

[单项选择]After years of strenuous work, the scientists are on the __________.of a great discovery of human gene.
A. domain
B. premise
C. threshold
D. pretext

[单项选择]After years of research,Charles Drew devised a procedure for preserving plasma.


A. transporting
B. saving
C. reusing
D. labeling

[单项选择]After years of research, Charles Drew devised a procedure for preserving plasma.
A. transporting
B. saving
C. reusing
D. labeling

[单项选择]After years of research, Dr. Duke ______ new ideas on the muses of dream.
A. brought up
B. brought about
C. came up
D. came about

[单项选择]Some scientists believe that dolphins have a language of their own.

[单项选择]In spite of______among a few scientists, and years of______discussion, the claim that earthquakes can be predicted with great precision prevails.
A. (A) antipathy … favorable
B. (B) skepticism … contentious
C. (C) mutualism … polite
D. (D) receptiveness … intelligent
E. (E) popularity … rancorous

[单项选择]After scientists did some research ______ the health of workers, the government tried to find some way to meet their demand.
A. into
B. off
C. about
D. for

[单项选择]Scientists have discovered in the past few years that ______.


A. the exposure of DNA to the public is unnecessary
B. the tiny cell in DNA is a neat little machine
C. man actually knows nothing about DNA
D. man has much to learn about DNA

[单项选择]

Scientists say they now have proof to support the old-fashioned advice that it’s best to sleep on a problem. They say sleep strengthens the memory and helps the brain organize the masses of information we receive each day. Lead researcher Bob Stickgold at the Harvard Medical School said, "Sleep helps us draw rules from our experiences. It’s like knowing the difference between dogs and cats. even if it’s hard to explain. " The US research team studied how well students remembered connections between words and symbols (象征) , reports New Scientist. They compared how the students performed if they had had a sleep between seeing the words and having the test, and if they had not slept. They found that people were better able to remember lists of related words after a night’ s sleep than after the same time spent awake during the day. They also found it easier to remember themes (主题) that the words had in common. But they forgot around one in four more
A. put together words of similar meanings
B. remember words and their meanings
C. show their knowledge of words
D. make up lists of related words