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David Bennett, a 57-year-old man from the US, received the world’s first pig heart transplant（移植）on January 7th, 2022. He died two months later on March 9th.

       It may sound like a failure, but it actually is a big step forward for xenotransplantation（异种器官移植）.
       Xenotransplantation has been a hot topic in medical research for many years.Doctors and scientists look for ways to solve the big problem of organ（器官）transplant waiting lists. In the US alone, over 100,000 patients are on a list waiting for new organs. Many of them will die before getting their chance to receive a heart, a kidney（肾）or other important organs. As a result, medical science has turned to animal organs.
       Doctors have experimented with xenotransplantation since the early 20th century. There are few success stories. Usually, patients’ bodies reject（排斥）the animal organs. Bennet lived much longer than other xenotransplantation patients. That’s because scientists removed pig genes（基因）that would cause fast rejection. Then they added human genes to help the body accept the organ.
       In fact, Bennett’s case was not the only success. Doctors at New York University attached（连接）gene-edited pig kidneys to a human patient’s blood vessels（血管）outside of the body in 2021. Doctors at University of Alabama put the gene-edited pig kidneys inside a patient’s body in the same year.
       Though these successes were short-lived, they show that there may be a way forward for xenotransplantation. “A lot of new information will come out. The development of this field will benefit from it and move forward at faster speed.” Muhammad Mohiuddin, director of the transplant program, told The Guardian.
1．How long did David Bennett live after the pig heart transplant?   ________

A．9 months

B．3 months.

C．2 months.

D．1 month.

2．What can we infer（推断）from Paragraph 3? ________

A．Human organs are expensive.

B．Many patients died because of the organ transplant.

C．Compared with human organs, animal organs are easier to get.

D．Patients cannot accept the animal organs in their bodies.

3．According to Paragraph 4, what may the main problem of xenotransplantation be? ________

A．Patients’ ideas.	B．Bodies’ rejection.
C．The high price.	D．The number of organs.

4．What does the underlined word “benefit” mean in Chinese in the last paragraph? ________

A．得益

B．赞扬

C．传播

D．涉及

5．What does the writer think of xenotransplantation?   ________

A．It should be stopped because of the death cases.

B．It has become more and more popular.

C．It is too difficult to carry on.

D．It is valuable and worth researching.