[单项选择]The longest time a human being can survive without sleep is probably ______ .


A. five days
B. seven days
C. ten days
D. twelve days

[单项选择]The longest time a human being can survive without sleep is probably ______.
A. five days
B. seven days
C. ten days
D. twelve days

[单项选择]Scientists and economists believe that human being can never use away all the mineral resources on Earth.（　）
A. believe
B. can never
C. use away
D. mineral

[单项选择]Every human being who has ever lived had two parents. Therefore, more people were alive three thousand years ago than are alive now.
The reasoning in the argument is flawed because it
A. overlooks the number of people in each generation during the last three thousand years who left no descendants.
B. disregards possible effects of disasters such as famines and plagues on human history.
C. overestimates the mathematical effect of repeated doublings on population size.
D. fails to take into account that people now alive have overlapping sets of ancestors.
E. (E) fails to consider that accurate estimation of the number of people alive three thousand years ago might be impossible.

[单项选择]The writer thinks human being's leaving the stage can be any of the following but __________.

[单项选择]

Placing a human being behind the wheel of an automobile often has the same curios effect as cutting certain fibres in the brain.
The result in either case is more primitive behaviour. Hostile feelings are apt to be ex pressed in an aggressive way.
The same man who will step aside for a stranger at a doorway will, when behind the wheel, risk an accident trying to beat another motorist through an intersection. The importance of emotional factors in automobile accidents is gaining recognition. Doctors and other scientists have concluded that the highway death toll resembles a disease epidemic and should be investigated as such.
Dr Ross A. McFarland, associate professor of industrial Hygiene at the Harvard University School of Public Health, aid that accidents "now constitute a greater threat to the safety of large segments of the population than diseases do."
Accidents are the leading cause of death between the ages of 1 and 35. About one th
A. psychopathic behaviour
B. an epidemic
C. hostile attitudes
D. antisocial behaviour

[单项选择]What is true about a human being in the future

[单项选择]If human being want to enjoy the long-lasting peace and happiness, they must avoid falling into war and live in ______ with each other.
A. coincidence
B. harmony
C. uniform
D. alliance

[单项选择]Every plant, animal, and human being needs water to ______ alive.
A. stay
B. make
C. run
D. glow