Two good friends, Sam and Jason, met with a car accident on their way home one night. The next morning, Sam woke up blind. His legs were broken. The doctor, Mr Lee was standing by his bed, looking at him with a thoughtful expression. When he saw Sam awake, he asked, “How are you feeling, Sam?” Sam smiled and said, “Not bad, Doctor. Thank you for doing the operation.” Mr Lee was moved by Sam. When he was leaving, Sam said, “Please don’t tell Jason about it.” “... OK.” Mr Lee replied.

Months later when Jason’s wounds (伤) healed, Sam was still very weak. Neither could he see or walk. What he could do was just stay in his wheelchair all day long. At first, Jason stayed with him for a few days. But days later, Jason felt very discouraged and embarrassed to spend time staying with a disabled man like Sam. So he went to see Sam less and less. He made new friends. From then on, he didn’t go to visit Sam any more. Sam didn’t have any family or friends other than Jason. He felt very sad.

Things went from bad to worse. Sam died a year later. When Jason came, Mr Lee gave a letter to him. It was from Sam. In the letter Sam said, “Dear Jason, I am disabled. But I want you to be a healthy man. So I gave my eyes to you so that you can enjoy life as a healthy man. Now you have new friends. I’m glad to see that you are as healthy and happy as usual. I’m glad you live a happy life. You are always my best friend ... ... Sam”. When he finished reading the letter , Mr Lee said, “I have promised that I will keep this a secret until Sam is gone. Now you know it.” Jason stood there. Tears ran down his face.

小题1: Why did Sam thanked the doctor?

A．Because the doctor was very friendly to him.

B．Because the doctor took good care of him.

C．Because the doctor saved his eyes.

D．Because the doctor kept the secret for him.小题2: Which of the following happened according to the order of time?

a. Jason felt very discouraged to stay with Sam.                                        

b. Jason lost his eyes in an accident.

c. Sam donated his eyes to Jason.       

d. Jason didn’t go to visit Sam any more.

e. Sam died and Jason knew the truth.       

A．dacbe

B．dcbea

C．bcade

D．bcdae小题3:The underlined word “healed” in the second paragraph is closest in the meaning to “__________”.

A．recovered

B．hurt

C．failed

D．disappeared小题4: It can be inferred from the passage that Sam was__________.

A．kind-hearted and helpful

B．discouraged and outgoing

C．optimistic and humorous

D．enthusiastic and curious

The human Y chromosome—the DNA chunk that makes a man a man—has lost so many genes over evolutionary time that some scientists have suspected it might disappear in 10 million years. But a new study says it’ll stick around.
Researchers found no sign of gene loss over the past 6 million years, suggesting the chromosome is "doing a pretty good job of maintaining itself," said researcher David Page of the Whitehead Institute for Biomedical Research in Cambridge, Mass.
That agrees with prior mathematical calculations that suggested the rate of gene loss would slow as the chromosome evolved, Page and study co-authors note in Thursday’s issue of the journal Nature. And, they say, it clashes with what Page called the "imminent demise" idea that says the Y chromosome is doomed to extinction.
The Y appeared 300 million years ago and has since eroded into a dinky chromosome, because it lacks the mechanism other chromosomes have to get rid of damaged DNA. So mutations have disabled hundreds of its original genes, causing them to be shed as useless. The Y now contains only 27 genes or families of virtually identical genes.
In 2003, Page reported that the modern-day Y has an unusual mechanism to fix about half of its genes and protect them from disappearing. But he said some scientists disagreed with his conclusion. The new paper focuses on a region of the Y chromosome where genes can’t be fixed that way.
Researchers compared the human and chimpanzee versions of this region. Humans and chimps have been evolving separately for about 6 million years, so scientists reasoned that the comparisons would reveal genes that have become disabled in one species or the other during that time.
They found five such genes on the chimp chromosome, but none on the human chromosome, an imbalance Page called surprising. "It looks like there has been little if any gene loss in our own species lineage in the last 6 million years," Page said. That contradicts the idea that the human Y chromosome has continued to lose genes so fast it’ll disappear in 10 million years, he said. "I think we can with confidence dismiss … the ’imminent demise’ theory," Page said.
Jennifer A. Marshall Graves of the Australian National University in Canberra, a gene researcher who argues for eventual extinction of the Y chromosome, called Page’s work "beautiful" but said it didn’t shake her conviction that the Y is doomed.
The only real question is when, not if, the Y chromosome disappears, she said. "It could be a lot shorter than 10 million years, but it could be a lot longer," she said.
The Y chromosome has already disappeared in some other animals, and "there’s no reason to expect it can’t happen to humans," she said. If it happened in people, some other chromosome would probably take over the sex-determining role of the Y, she said.

It can be inferred from the first 3 paragraphs that
[A] the human Y chromosome has stopped evolution.
[B] a man will no longer be a man in 10 million years.
[C] scientists are divided on the latest issue of Y chromosome.
[D] mathematical calculations are important in genetic studies.