题目内容：

Chinese scientists have found a new way to use cells found in human urine （尿液）that could aid in the treatment of a range of nerve disorders.That is a new technique for reprogramming cells in human urine into nerve progenitor cells  that can grow into multi-functional nerve and brain cells.

The technique is expected to be used in the study and treatment of nerve disorders such as Parkinson's disease, Alzheimer's disease and other nerve disorders.

Pei Duanqing, a professor at Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, said his research team has combined an episomal system to deliver reprogramming factors with a chemically defined culture medium to reprogram kidney epithelial(肾表皮) cells in urine into NPCs.

These NPCs, normally only found in the human brain, were later proven to be transgene-free and self-renewing, he said.

"These nerve and brain cells can survive for up to one month when transplanted into the brain of a newborn rat," said Pei. "My team is working hard to understand why our experimental condition allowed the urine cells to become NPCs, because we want to improve the technique and make it more efficient".

Scientists have long searched to treat and study neural disorders by obtaining and transplanting neural stem cells. However, the previous method of getting and using cells from either fetal (胎儿)or adult human tissue remains challenging due to ethical concerns and immune system rejections, he said.

Pei hopes the discovery will be used to generate NPCs from patients with nerve disorders such as Parkinson's disease. "These NPCs from patients may help us discover new drugs for these diseases."

"It is a remarkable advance in the stem cell field. The results and methods obtained from this study will be of great value and significance to the field, " said Fred Gage,a professor with the Salk Institute for Biological Studies.

1.What is the passage mainly about?

A. NPCs are beneficial in treating human diseases.

B. Chinese scientists succeeded in making NPCs from human urine.

C. Chinese scientists have found cures for all diseases.

D. A new technique was used to study the use of human urine

2.Pei and his tean try their best to work hard in order to       .

A. make more contributions to medical study

B. discover another new technique

C. make the technique more perfect

D. treat more patients suffering from bad diseases

3.What is the challenge of making NPCs in the previous method?

A. The ethical comcerns and immune system refusal

B. The difificulties in getting cells from human.

C. The under-developed techniques in medical science.

D. The lack of financial support from the government.

4.From the last paragraph we can infer       .

A. the new technique will be developed in science

B. the results and methods will be applied to treating cancers

C. the study will give a major push to the stem cell field

D. the mew technique will bring great profis