单选题The failure to talk to each other causes all of the following EXCEPT

单选题[此试题无题干]

单选题Questions 14—16 are based on the following passage. You now have 15 seconds to read the Questions 14—16.

单选题 For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic and nationalistic. Columbus went west to look for better trade routes to the Orient and to promote the greater glory of Spain. Lewis and Clark journeyed into the American wilderness to find out what the US had acquired when it purchased Louisiana, and the Appolo astronauts rocketed to the moon in a dramatic show of technological muscle during the cold war. Although their missions blended commercial and political-military imperatives, the explorers involved all accomplished some significant science simply by going where no scientists had gone. Today Mars looms as humanity's next great terra incognita. And with doubtful prospects for a short- term financial return, with the cold war a rapidly fading memory and amid a growing emphasis on international cooperation in large space ventures, it is-clear that imperatives other than profits or nationalism will have to compel human beings to leave their tracks on the planet's reddish surface. Could it be that science. which has long played a minor role in exploration, is at last destined to take a leading role? The question naturally invites a couple of others: Are there experiments that only humans could do on Mars? Could those experiments pro- vide insights profound enough to justify the expense of sending people across interplanetary space? {{U}}With Mars the scientific stakes are arguably higher than they have ever been{{/U}}. The issue of whether life ever existed on the planet, and whether it persists to this day, has been highlighted by mounting evidence that the Red Planet had abundant stable, liquid water and by the continuing controversy over suggestions that bacterial fossils rode to Earth on a meteorite from Mars. A more conclusive answer about life on Mars, past or present, would give researchers invaluable data about the range of conditions under which a planet can generate the complex chemistry that leads to life, If it could be established that life arose independently on Mars and Earth, the finding would provide the first concrete clues in one of the deepest mysteries in all of science: the prevalence of life in the universe.

单选题[此试题无题干]

单选题Until the twentieth century cigarettes were not an important threat to public health. Men used tobacco mainly in the form of cigars, chewing tobacco, pipe tobacco, and snuff(鼻烟). Most women did not use tobacco at all. The cigarettes industry began in the 1870s with the development of the cigarette manufacturing machine. This made it possible to produce great numbers of cigarettes very quickly, and it reduced the price. Today cigarette smoking is a widespread habit. About forty-three percent of adult men and thirty-one percent of adult women in the United States smoke cigarettes regularly. It is encouraging to note, however, that millions of people have given up the smoking habit. Seventy-five percent of the male population and forty-six percent of the female population have smoked cigarettes at some time during their lives, but twenty-six percent of these men and eleven percent of women have stopped smoking. The number of persons who have given up smoking is increasing. Men as a group smoke more than women. Among both men and women .the age group with the highest proportion of smokers is the age group 24-44. Income, education and occupation' all play a part in determining a person's smoking habits. City people smoke more than people living on farms. Well-educated men with high incomes are less likely to smoke cigarettes than men with fewer years of schooling and lower incomes. On the other hand, if a well-educated man with a higher income smokes at all, he is likely to smoke more packs of cigarettes per day. The situation is somewhat different for women. There are slightly more smokers among women with higher family incomes and higher education than among the lower income and lower educational groups. These more highly educated women tend to smoke more heavily. Among teenagers there are fewer smokers from upper-in-come, well-educated families, and fewer from families living in farm areas. High school students who are preparing for college are less likely to smoke than those who do not plan to continue their education after high school. Children are most likely to start smoking if one or both of their parents smoke.

单选题

单选题It can be inferred that doctors are able to determine hospital policies because

单选题The immigrants' flushing in was considered a threat to American value mainly because

单选题

单选题 Questions 11--13 are based on the following news on teeth protection. You now have 15 seconds to read Questions 11--13.

单选题What does the author mean by "most people are literally having a ZZZ" (Line 2, Para. 5)?

单选题The word "galvanize" in paragraph 4 is closest in meaning to______.