People laugh and people cry. But it is thought that emotions such as anger, or joy, typically make Americans feel uncomfortable and embarrassed. The shedder of tears(落泪者) is likely to apologize, even when a great tragedy was the cause. The observer of tears is likely to do everything possible to put an end to the emotional tears. But judging from recent studies of crying behavior, both those responses to tears are often inappropriate and may even be counterproductive (适得其反).
Humans are the only animals clearly known to shed emotional tears. Since evolution has given rise to few purposeless physiological responses, it is logical to assume that crying has one or more functions that increase survival.
Although some observers have suggested that crying is a way to ask for assistance form others (as a crying baby might from its mother), the shedding of tears is hardly necessary to get help. Vo-cal (出声的) cries would have been quite enough, more likely than tears to gain attention. So, it appears that there must be something special about tears themselves.
Indeed, the new studies suggest that emotional tears may play a direct role in easing stress.   University of Minnesota researchers who are studying the chemical composition of tears have recently separated 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.
Other researchers are looking into the usefulness of tears as a means of diagnosing human ills and monitoring drugs. At Tulane University’s Teat Analysis Laboratory Dr. Peter Kastl and his colleagues report that they can use tears to detect drug abuse, to study the causes of "dry eye" syndrome(综合症) and the effects of eye surgery, and perhaps even to measure exposure to environmental pollutants.
What does the phrase "both those responses" in Paragraph 1 refer to?

A．Crying out of sorrow and shedding tears for happiness.

B．The embarrassment and unpleasant feelings of the observers.

C．Linking illness with crying and finding the chemical composition of tears.

D．The tear shedder’s apology and the observer’s effort to stop the crying.

It is known from the first paragraph that____.

A．shedding tears gives unpleasant feelings to Americans

B．crying may often result in tragedy

C．crying usually wins sympathy from other people

D．one who sheds tears in public will be blamed

What does the author say about crying?

A．It is a pointless physiological response to the environment.

B．It must have a role to play in man' s survival.

C．It is meant to get attention and assistance.

D．It usually produces the desired effect.

From the passage we can infer that____.

A．it is unnatural for people to shed tears

B．we can reduce our stress by shedding tears

C．shedders of tears can' t get help by crying loudly

D．unlike animals, humans can shed tears for survival