题目内容：

    Sometimes, you just can't help it. Maybe you're watching a sad movie, or thinking about the friend who moved away. Next thing you know, you feel pressure in your throat, your eyes are watering, and you have tears running down your cheeks.

According to Ad Vingerhoets, a professor of psychology at Tilburg University, in the Netherlands, who is one of the few scientists in the world who have studied crying, there are three types of tears. Basal tears are the first type. They act as a protective barrier between the eye and the rest of the World. Next are reflex tears. They wash your eyes clean when something gets in them. Finally, there are emotional tears. “These are released in response to emotional states,” explains Vingerhoets.

Scientists believe crying has something to do with how humans developed and learned to depend on each other. “Humans are very complex social creatures,” says Lauren Bylsma, a professor at the University of Pittsburgh, in Pennsylvania. "It seems that tears serve to arouse help and support from others,” She says.

Vingerhoets agrees, "I think that the reason why humans shed tears（流眼泪）has something to do with our childhood, " he says. "that's the time when we are still dependent on adults for love and protection and care. The major advantage of emotional tears is that you can target them at a specific person." Vingerhoets says this ability could have come in handy in prehistoric times, when humans were living among dangerous animals. Tears were a safer way to get attention. "In this case, it is better to use a silent signal to ask for help, "he says.

Vingerhoets and Byhma do frequent studies to better understand why humans cry. According to Byhma, there is still much more to discover. "It's surprising, "she says, "how much we still don't know.”

1.In the scientists' opinion, crying is ________.

A.a sign of human evolution B.a result of human kindness

C.a cause of personal growth D.a means of relying on each other

2.The underlined phrase "this ability" in the last paragraph refers to the ability to ________.

A.seek help wisely B.aim tears at someone

C.cry emotionally D.appeal to other people

3.From the text, we learn that Ad Vingerhoets and Lauren Bylsma ________.

A.hold different opinions about the causes of tears

B.think positively of the effects of tears

C.are working together to study tears

D.have learned enough about tears

4.What can be a suitable title for the text?

A.The types of tears B.The components of tears

C.The science of tears D.The opinions about tears