题目内容：

    After decades of cat-and-mouse between athletes and the word anti-doping agency (WADA), athletes found what they must have believed to be the ultimate (终极的) doping agent: their own blood. To enhance athletic performance with your own blood, you draw your blood and store it in a freezer. Your body compensates by creating more blood. Then, months later, just before a competition, you can re-inject (注射) the old blood for a boost. As the red-blood-cell count goes up, so does an athlete’s ability to absorb oxygen. The more oxygen you get with each breath, the more energy your body is able to bum and the better you are able to perform.

Although the enhancement is small compared to actual drugs, it can be the difference between a gold medal and a silver medal. Best of all, “extra blood” was never something WADA tested for.

But WADA wasn’t going to sit by and be fooled. What it came up with in response might be a solution to stop doping once and for all: an athlete biological passport (ABP). The idea is to record some biological features of an athlete through testing done at regular intervals. The biological passport’s partial implementation (实施)—recording blood and steroid levels—began in January 2014.

When all necessary biological features are finally combined, WADA will no longer need to worry about finding new methods to detect a drug. It will only have to detect (检测) resulting changes in the body. In the case of blood doping, if the athlete’s normal red-blood-cell count is, say, 47%, but then is found to be 51% after a competition, cheating may have been involved.

WADA is confident that the biological passport could even prevent genetic changes—the ultimate, ever-lasting enhancement—which are surely coming next. If an athlete inserts a performance enhancing gene, it will probably leave detectable changes in the body, that would differ from the athlete’s feature in the biological passport.

1.What does the underlined word “boost” in Paragraph 1 probably mean?

A. Treatment. B. Test.

C. Promotion. D. Recovery.

2.What words can be used to describe the athlete biological passport?

A. Complex and expensive. B. Simple and thorough.

C. Flexible an popular. D. Controversial and confusing.

3.What s the writer’s attitude towards the solution of anti-doping mentioned in the text?

A. Suspicious. B. Positive.

C. Worried. D. Unconcerned.

4.What can we infer about the athlete biological passport?

A. It can only be used to test blood doping.

B. It has been completely adopted by WADA.

C. It is the excellent alternative of many athletes.

D. It’s a good choice to ensure faimess in sports