Autism spectrum disorder is a developmental disability. People with autism have trouble communicating and with social skills. The U.S. Centers for Disease Control and Prevention says the person also might repeat some behaviors and not want change in their daily activities. Some people with the condition need a lot of help. Others need less. 

CDC officials say autism affects one in every 68 children in the United States. More boys than girls are believed to have the condition. But the number of cases appears to be growing. It is unclear whether the growing number shows a real increase or comes from more knowledge about this disorder.

Common signs of autism include trouble making eye contact and a delay in learning how to speak. Some people with severe autism never learn how to talk. Many people with autism also have difficulty understanding facial expressions and the feelings of others. They also have trouble making friends of the same age.

Doctors have learned how to recognize autism, but much is still unknown about its causes.

Researchers at Harvard University have come closer to finding answers. They found that women exposed to the highest levels of fine particulate air pollution late in their pregnancies are two times more likely to give birth to a child with autism. The researchers found that the timing of exposure to pollution was important. They found no increased risk of autism in children whose mothers were around high levels of pollution before becoming pregnant. And the study found air pollution does not seem to increase the risk of children developing autism after they are born. 

Marc Weisskopf led the Harvard researchers. He says pregnant women should avoid air pollution as much as possible. But he warns that other things may increase the risk of autism spectrum disorder.

Autism is believed to result from a combination of environmental and genetic factors.

For now, Marc Weisskopf says researchers are trying to identify the exact substances in air pollution that increase the risk of autism.

本时文内容由奇速英语国际教育研究院原创编写，禁止复制和任何商业用途，版权所有，侵权必究！

1.What’s the main idea of the passage?

A Researchers’ fight against autism.

B Behaviors of children with autism.

C Effects and possible causes of autism.

D Common signs of severe autism.

解析：选C。C 主旨大意题。根据前4段中People with autism have trouble…，…autism affects…, Common signs of autism…, Doctors have learned how to recognize autism, but much is still unknown about its causes等句，可知本文是在介绍自闭症对患者的影响及其可能的诱因，故选C。

2.How many children may suffer from autism in the US in the future?

A Just one child out of every 68 children.

B Over one out of every 68 children.

C Just one girl out of every 68 girls.

D Over one out of every 68 boys.

解析：选B。B 细节理解题。根据第2段…autism affects one in every 68 children in the United States…But the number of cases appears to be growing，可知，病例还在增长，68个孩子中患病的人数应大于1，故选B。

3.What’s the common sign of people with autism?

A Having trouble making eye movement.

B Having difficulty expressing their feelings.

C Having trouble making facial expressions.

D Having difficulty picking up a language.

解析：选D。D 细节理解题。根据第3段…a delay in learning how to speak，可知患自闭症的人，学话迟缓， 故选D。

4.Which child is more likely to develop autism?

A His mother lives around bad air pollution before pregnancy.

B His mother lives around bad air pollution in the late pregnancy.

C His mother lives around bad air pollution in the early pregnancy.

D His mother lives around bad air pollution after giving birth to him.

解析：选B。B 细节理解题。根据第5段…women exposed to the highest levels of fine particulate air pollution late in their pregnancies are two times more likely to give birth to a child with autism，可知，在怀孕后期处于细颗粒物空气污染中的妇女生下患自闭症婴儿的几率会翻番，故选B。

5.From the passage, we can infer that ______.

A autism can easily be cured with the modern medicine

B autism is deadly disease that troubles the whole world

C autism will be better treated after its causes are found

D autism is caused with environmental and genetic factors

解析：选C。C 推理判断题。由文中Researchers at Harvard University have come closer to finding answers以及…researchers are trying to identify the exact substances in air pollution that increase the risk of autism等句，可知研究者离发现自闭症的成因已不远了，知道其成因后，对症施治，效果一定会好起来，故选C。