Glaucoma（青光眼）is a major cause of blindness around the world, especially in developing coun

Glaua（青光眼）is a major cause of blindness around the world, especially in developing countries. The World Health Organization says glaua is a greater public health challenge than cataracts（白内障）, because the blindness caused by the latter can be cured after operations.
Glaua 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't 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 glaua. “The glaua we see in sub-Saharan Africa is a much more aggressive blinding disease than the glaua 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 glaua.” Age is another thing that may lead to glaua, although people of all ages can get it.
Glaua is a group of diseases that monly 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．There's an area around the edge of the watch that drains（使排出）the liquid. When that drain is blocked, the liquid can't 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, glaua can be controlled. Glaua is not curable. But as  researchers worldwide lean more about it, they grow more hopeful that glaua can one day be cured or even prevented.
【小题1】In which country is glaua 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 glauaB．People in developed countries hardly develop glauaC．Glaua only causes blindness among old peopleD．The research on glaua is still going on worldwideC