单选题 Crying is hardly an activity encouraged by society. Tears, whether they are of sorrow, anger, or joy, typically make Americans feel uncomfortable and embarrassed. The shedder of tears is likely to apologize, even when a devastating tragedy was the provocation. The observer of tears is likely to do everything possible to put an end to the emotional outpouring. But judging from recent studies of crying behavior, links between illness and crying and the chemical composition of tears, both those responses to tears are often inappropriate and may even be counterproductive .
Humans are the only animals definitely known to shed emotiomal tears. Since evolution has given rise to few, if any, purposeless physiological responses, it is logical to assume that crying has one or more functions that enhance survival.
Although some observers have suggested that crying is a way to elicit assistance from others (as a crying baby might from its mother), the shedding of tears is hardly necessary to get help. Vocal cries would have been quite enough, more likely than tears to gain attention. So, it appears, there must be something special about tears themselves.
Indeed, the new studies suggest that emotional tears may play a direct role in alleviating stress. University of Minnesota researchers who are studying the chemical composition of tears have recently isolated two important chemicals from emotional tears. Both chemicals are found only in tears that are shed in response to emotion. Tears shed because of exposure to cut onion would contain no such substance.
Researchers at several other institutions are investigating the usefulness of tears as a means of diagnosing human ills and monitoring drugs.
At Tulane University"s Tear Analysis Laboratory Dr. Peter Kastl and his colleagues report that they can use tears to detect drug abuse and exposure to medication, to determine whether a contact lens fits properly of why it may be uncomfortable, to study the causes of "dry eye" syndrome and the effects of eye surgery, and perhaps even to measure exposure to environmental pollutants.
At Columbia University Dt. Liasy Faris and colleagues are studying tears for clues to the diagnosis of diseases away from the eyes. Tears can be obtained painlessly without invading the body and only tiny amounts are needed to perform highly refined analyses.

【正确答案】 B

【答案解析】[解析] 推断题。第一段共五句话。第一句概括说哭泣在美国是不受欢迎的。接下来的三句是对第一句的解释，哭泣的人要道歉，看见哭泣的人要阻止哭泣。最后一句话是最近研究表明这些行为对健康十分不利。由此可见both those responses to tears是指shedder of tears is likely to apologize...observer of tears is likely to do everything possible to put an end to the emotional outpouring，因此B项是对此的概括。