更多"Because car crashes are usually cau"的相关试题:
[单项选择]Chronic back pain is usually caused by a herniated or degenerated spinal disk. In most cases the disk will have been damaged years before chronic pain develops, and in fact an estimated one in five people over the age of 30 has a herniated or degenerated disk that shows no chronic symptoms. If chronic pain later develops in such a case, it is generally brought about by a deterioration of the abdominal and spinal muscles caused by insufficient exercise.
The statements above, if true, most strongly support which one of the following
A. Four out of five people over the age of 30 can be sure they will never develop chronic back pain.
B. People who exercise their abdominal and spinal muscles regularly are sure to be free from chronic back pain.
C. Patients rarely suffer even mild and fleeting back pain at the time that a spinal disk first becomes herniated or degenerated.
D. Doctors can accurately predict which people who do not have chronic back pain will develop it in the future.
E. (E) There is a strategy that can be effective in delaying or preventing the onset of pain from a currently asymptomatic herniated or degenerated spinal disk.
[单项选择]
Most forest fires are caused by human carelessness, negligence, or ignorance. Forest fire prevention, therefore, is mainly a problem of creating a better understanding of the importance of forests, an awareness of the danger of fire in the woods, and a sense of personal responsibility to safeguard the forests from danger. This is not an easy job. A city dweller, used to paved streets, does not easily change his smoking habits when he goes into the woods.
Careless smokers are responsible for thousands of forest fires each year. Many of these are started when cigarette butts and matches are thrown from automobiles. Others are caused by hunters, hikers, fishermen, or woods workers who are careless in disposing of their smoking materials. The Forest Service has posted rules in many of the National Forests that prohibit smoking except in certain designated areas. Many of the states have laws against throwing lighted materials from automobiles. The prevention of smoker-caused f
A. smoking in forests
B. the chief causes of forest fires and their prevention
C. changing the attitudes and behavior of millions of people
D. advances in knowledge of fire weather
[单项选择]—What do you usually do at weekends
—Er... I usually ______ some cleaning at home.
A. make
B. take
C. do
[单项选择]______ human behavior may be caused by eating substances that upset the delicate chemical balance in the brain.
A. Deliberate
B. Consistent
C. Primitive
D. Abnormal
[单项选择]Jack usually went to school in his father's car.
[单项选择]
Prolonging Human Life
Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion.
Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of famine, infants might be allowed to die because they could not survive if their parents starved, whereas if the parents survived they could have another child. In most contemporary societies, people feel a moral obligation to keep people alive whether t
A. the industrial development
B. an increase in birthrates
C. cultural advances
D. a decrease in death rates
[单项选择]
Prolonging Human Life
Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion.
Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of famine, infants might be allowed to die because they could not survive if their parents starved, whereas if the parents survived they could have another child. In most contemporary societies, people feel a moral obligation to keep people alive whether they
A. an increase in birthrates
B. the industrial development
C. a decrease in death rates
D. cultural advances
