[单项选择]Brown rats are dangerous because （）.
A. they carry fleas which give men bubonic plague
B. they come with typhus
C. they carry thirty-five diseases
D. they killed 200 million people

[单项选择]Human beings are afraid of rats mainly because （）.
A. rats have clever leaders
B. rats are clever than men
C. rats steal men's food
D. rats killed hundreds of millions of men

[单项选择]Because Mr Brown was ill,______he didn't come yesterday.


A. so
B. or
C. /

[单项选择]Mr. Brown often (wore) a heavy coat because he was not (used to) (live) in such a (cold climate).
A. wore
B. used to
C. live
D. cold climate

[单项选择]Anold Brown changed his name because_______.


A. there was racial discrimination in employment
B. Brown was just the same as Braunowiitz
C. it was easy to write
D. Brown sounds better

[单项选择]Why did file people kill the rats


A. To get some money.
B. Because the rats attacked them at night.
C. To help the city office to make the city clean.

[单项选择]The rats fed unrestricted diets do NOT
A. have one preventing-aging protein increased.
B. have their cell death increased or doubled.
C. have their DNA fragmentation doubled.
D. have the levels of proteins increased.

[单项选择]Information on behavioral deficits in rats is also______to humans, but there is an enormous step between the psychology of the two species, so we must be careful about declaring such data______.
A. (A) applied… invalid
B. (B) extrapolated … dissimilar
C. (C) obscure … sound
D. (D) relevant … analogous
E. (E) inapplicable … similar

[单项选择]The experiments of two groups of rats indicate that _______.

[单项选择]Besides carrying diseases, rats also （）.
A. take men's food
B. live in cities and villages
C. know how to identify poison food
D. all of the above

[单项选择]When the mongooses in Jamaica killed off the rats they ______.
A. attacked the humans
B. ate the sugar crop
C. became problems themselves
D. had nothing to eat

[单项选择]

When lab rats sleep, their brains revisit the maze they navigated during the day, according to a new study (1) yesterday, offering some of the strongest evidence (2) that animals do indeed dream. Experiments with sleeping rats found that cells in the animals’ brains fire in a distinctive pat tern (3) the pattern that occurs when they are (4) and trying to learn their way around a maze.
Based on the results, the researchers concluded the rats were dreaming about the maze, (5) re viewing what they had learned while awake to (6) the memories.
Researchers have long known that animals go (7) the same types of sleep phases that people do, including rapid-eye-movement (REM) sleep, which is when people dream. But (8) the occasional twitching, growling or barking that any dog owner has (9) in his or her sleeping pet, there’s been (10) direct evidence that animals (11) . If animals drea
A. cry
B. memorize
C. dream
D. sleep