问题补充：
Glaucoma（青光眼）is a major cause of blindness around the world, especially in developing countries. The World Health Organization says glaucoma is a greater public health challenge than cataracts（白内障）, because the blindness caused by the latter can be cured after operations.
Glaucoma is a disease that makes people around the world lose their sight, and they usually don’t even know they have the disease until it has permanently destroyed at least 40 percent of their sight. The process is usually so painless and subtle（不明显的）, so people don notice it. Actually, the simplest medical test can discover it.
“It is the leading cause of blindness in the United States. In Hispanics and in African-Americans, it’s the second leading cause of blindness and so is the case in the Chinese and Indians.” said Dr. Alan Robin, a specialist in treating glaucoma. “The glaucoma we see in sub-Saharan Africa is a much more aggressive blinding disease than the glaucoma we see in Americans or even African- Americans in-the United States.” he said．．
Dr. Eric Fleischer also sees these differences at Medstar Washington Hospital Center. “Pretty much anybody who has ancestors in Africa has an increased chance of developing glaucoma.” Age is another thing that may lead to glaucoma, although people of all ages can get it.
Glaucoma is a group of diseases that commonly produce pressure in the eye. An eye is sort of like a watch. And behind the face of the watch, liquid is made. It goes through your pupil（瞳孔）and into the front of the watch between the face and the crystal．Theres an area around the edge of the watch that drains（使排出）the liquid. When that drain is blocked, the liquid can leave the eye as fast as it is produced. The rising pressure within the eye damages and eventually kills the optic（视觉的） nerve. The result is blindness.
Fortunately, if caught early, glaucoma can be controlled. Glaucoma is not curable. But as researchers worldwide lean more about it, they grow more hopeful that glaucoma can one day be cured or even prevented.
【小题1】In which country is glaucoma the biggest danger to people’s sight?A．In ChinaB．In IndiaC．In the USAD．In Japan【小题2】What do the underlined words “these differences”（in Para 4 ）refer to?A．The differences in regions（地区）B．The cultural differencesC．The differences in ageD．The physical differences【小题3】From the passage, we can learn that, .A．It is hard for medical tests to discover glaucomaB．People in developed countries hardly develop glaucomaC．Glaucoma only causes blindness among old peopleD．The research on glaucoma is still going on worldwideC
答案：
(答案→)C
解析：文章介绍了青光眼的形成和危害，以及不同地区青光眼的危害的差异。
【小题1】细节题：从第三段的句子：“It is the leading cause of blindness in the United States. 可知在美国青光眼对人们的视力是最大的威胁。选C
【小题2】推理题：文章第三段主要讲了青光眼地区分布的差异。第四段里面的differences就是“地区差异”。选A
【小题3】细节题：从最后一段的句子：But as researchers worldwide lean more about it, they grow more hopeful that glaucoma can one day be cured or even prevented.可知对青光眼的研究还在全世界进行。选D
