Winning is usually a cause for celebration,       may not be so for US president Barack Obama,      won the Nobel Peace Prize on October 9.

   A. it ; which   B.which ; which      C. which ; whom      D. which ; who

Most of the artists _______ to the party were from South Africa.

A. invited         B. to invite  C. being invited     D. had been invited         

The sports meet, originally due to be held last Friday, was finally _______ because of the bad weather. 

A. set off  B. broken off       C. worn off      D. called off 

 I tried to work on, but I got so tired that I could no longer ________. 

A. keep out     B. come down        C. come up      D. hold out 

 The picture of the park ________ memories of our class trip last year. 

A. took up     B. came up         C. turned up    D. called up 

 She______ his number in the phone book to make sure that she had got it right. A. looked up     B. looked for          C. picked out    D. picked up 

 If you ______ any problems when you arrive at the airport, give me a ring． 

A. come up with   B. set about        C. run into     D. put aside 

The strong evidence as well as these new facts _____ prove the prisoner’s innocence the next time the case comes to trial.

A. is going to                B. are going to              C. was going to             D. were going to

－I don’t want to move to that city. It is heavily polluted.

－Pollution is common. The city here is       .

A. no less clean                B. not cleaner                   C. no cleaner           D. not less clean

British and American scientists are raising genetically modified(转基因的) pigs in the hope of providing organs for transplant(移植) to humans, the project leader wrote in a newspaper Sunday.

Scientists in London and California have begun conducting the genetic experiments to find a solution to record–long waiting lists for organ transplants, Robert Winston said in an opinion piece written for Britain's Sunday Times.

In Britain alone, around 8,000 patients are waiting for a transplant.

"People needing a new heart or liver are waiting for someone else to die – usually a violent death in a traffic accident," Winston wrote in the newspaper. He said his team was "trying to modify pigs so their organs might save the lives of humans."

The scientists are introducing human genes into the animals to reduce the chances of the organs being rejected by patients, as has been common in previous attempts to use animal tissues, said Winston, who heads the Institute of Reproductive and Developmental Biology at London's Hammersmith Hospital.

Working with Dr. Carol Redhead of the California Institute of Technology, Winston's team has injected human genes directly into male piglets(猪仔), adding them to the animal's sperm(精子).

He said that pigs involved in experiments had successfully produced transgenic sperm, but acknowledged that British and European laws had prevented the team from using the pigs to mate.

The Sunday Times newspaper reported that the experiments would be moved to the United States following difficulties with funding and regulations in Britain. It said the pigs would be bred in Missouri.

"Our U.S. friends will benefit from our technology and the income we might have produced for Britain will be lost," Winston wrote.

Some scientists have previously blamed the idea of using animal organs for human transplant, saying the technique risks spreading animal viruses to humans. Winston said his research project is attempting to breed virus-free pigs.

49. Scientists are introducing human genes into the animals to ____________.

50. Some scientists have blamed the idea of using animal organs for human transplant because ____________.

51. According to Winston, it seems ___________ to Britain to move the experiments to the United States.            

52. It can be inferred from the passage that ____________.