题目内容：

Researchers in China and the United States have developed a new cataract(白内障)treatment with cells that has restored vision in babies in a trial and may eventually be used in adults.

The treatment- by doctors and staff members at the University of California, San Diego School of Medicine and Sichuan and Sun Yat-sen universities in China-was published in March 9 edition of the scientific journal Nature.

A cataract is a clouding of the normally clear lens(晶体)of an eye. Typical cataract operation involves the removal of the cloudy lens and the insertion of an artificial one. The new operation has been tested in animals and during a small, human trial. It resulted in fewer complications(并发症)than the current harmful operation, and in regrown lenses with superior visual function in all 12 of the baby cataract patients who received the procedure.

A congenital cataract- lens clouding that occurs at birth or shortly after- is important cause of blindness in children. In the new research, Kand Zhang, head of ophthalmic genetics at US San Diego’s Shiley Eye Institute, and his colleagues relied on the regrown potential of endogenous(同源的)stem cells.

According to Zhang, endogenous stem cells are different from other stem cells that are typically grown in a laboratory, transplanted into a patient, and can have risks of immune（免疫的）rejection, infection or cancers. Zhang told CBS News, “We invented a new operation to make a very small opening at the side of a cataractous lens bag, remove the cataract inside, allow the opening to heal, and promote potential lens stem cells to regrow an entirely new lens with vision.”

The human trial involved 12 babies under the age of 2 who were treated with the new method, while 25 babies received thee standard operation care.. The latter group experienced a higher incidence of pos- operation danger, early- onset eye high blood pressure and increased lens clouding. The scientists reported fewer complications and faster healing among the 12 babies who has the new procedure.

1.What is the text mainly about?

A. The concept of the cataract

B. A new cataract treatment with stem cells

C. Bad effects of post-operation in the cataract

D. The reasons why the cataract comes into being

2.Which of the following best describe the new cataract treatment according to the passage?

A. Convenient    B. Comfortable

C. Cheap    D. Safe

3.What can we learn about the new cataract treatment?

A. It has more risks

B. It may be used widely

C. It has been put into practice widely

D. It can only restore vision in babies

4.What does the underlined word “congenital” in the fourth paragraph mean?

A. Born    B. Strange

C. Serious    D. Dangerous.