1 . 阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

The Great Wall     1    (think) highly of by the human race as one of the Seven Wonders of the Ancient World. It lies in North China, with over 6,000 kilometers in     2    (long) and 7—8 meters in height.     3    (build) mainly with earth, brick and stone, the Great Wall was designed     4    (protect) people in ancient China from invaders. However, it is now     5    (universal) regarded as one of the most important tourist spots in our country. Every year, it is visited by thousands of people from all over the world. The Great Wall has become a symbol of     6     Chinese nation and its culture.

The Great Wall is wide enough for five horses or ten men to walk side     7     side. Along the wall are watch towers, where soldiers used to watch.

It was very difficult to build such a wall in ancient times without any modern     8    (machine). The condition was     9     terrible that all the work was done by hand. To be honest, the Great Wall was made not only of stone     10     earth, but of the flesh and blood of millions of men.

2 . Eating too much fatty food, exercising too little and smoking can raise your future risk of heart disease. But there is another factor that can cause your heart problems more immediately：the air you breathe.

Previous studies have linked high exposure (暴露) to environmental pollution to an increased risk of heart problems，but two analyses now show that poor air quality can lead to heart attack or stroke (中风) within as little as a few hours after exposure. In one review of the research, scientists found that people exposed to high levels of pollutants (污染物) were up to 5% more likely to suffer a heart attack within days of exposure than those with lower exposure. A separate study of stroke patients showed that even air that the U. S. Environmental Protection Agency (EPA)considers to be of “moderate” (良好) quality and relatively safe for our health can raise the risk of stroke as much as 34% within 12 to 14 hours of exposure.

The authors of both studies stress that these risks are relatively small for healthy people and certainly modest compared with other risk factors such as smoking and high blood pressure. However, it is important to be aware of these dangers because everyone is exposed to air pollution regardless of lifestyle choices. So stricter regulation by the EPA of pollutants may not only improve environmental air quality but could also become necessary to protect public health.

1. The text mainly discusses the relationship between ________.

A．heart problems and air quality

B．heart problems and exercising

C．heart problems and smoking

D．heart problems and fatty food

2. The underlined word “modest” in Paragraph 3 most probably means ________.

A．relatively high	B．extremely low
C．relatively low	D．extremely high

3. What can we learn from the text?

A．Eating fatty food has immediate effects on your heart.

B．The EPA conducted many studies on air quality.

C．Moderate air quality is more harmful than smoking.

D．Stricter regulations on pollutants should be made.

4. The author's purpose of writing the text is most likely to ________.

A．inform	B．persuade
C．describe	D．entertain