Question

A bite from a tsetse fly is an extremely unpleasant experience. To make matters worse, several species of tsetse fly can transmit diseases. One of the most dangerous is a parasite(寄生虫) that causes "sleeping sickness".

After the initial bite, sleeping sickness symptoms often start with a fever, headaches and aching muscles. As the illness goes on, those infected become increasingly tired, which is where it gets its name.

It is worth noting that sleeping sickness is no longer as deadly as it once was. In the early 20^th Century several hundred thousand people were infected each year. By the 1960s the disease was considered "under control" and had reached very low numbers, making its spread more difficult. But in the 1970s there was another major infection, which took 20 years to control. Since then, better screening programs and earlier treatments have reduced the number of cases dramatically. In 2000 this figure dropped to fewer than 3,000. The World Health Organization (WHO) hopes the disease will be completely removed by 2020. More problematically, a series of new studies have shown that the parasite is more complicated than previously believed.

Sleeping sickness has always been considered—and analyzed—as a blood disease, because the parasites can readily be discovered in the blood of its victims. However, in a recent study found that the parasite can stay in the skin and fat, as well as in the blood. There may even be a higher density（密度）of the parasite in the skin than in the blood. That means a person can have no symptoms but still both harbor the disease and spread it. The finding could explain the mysterious 1970s infection, and why the disease can spring up in areas that had previously been cleared.

1.What's the danger of a tsetse fly bite?

A. It makes people sleepy.    B. It causes skin disease.

C. It brings about deaths.    D. It transmits deadly parasites.

2.What can we infer about sleeping sickness from Paragraph 3?

A. It's still a threat to human health.

B. It's not that dangerous at present.

C. It's incurable in the early 20^th century.

D. It's completely under control in the 1960s.

3.What does the underlined "harbor" most probably mean?

A. carry    B. resist    C. exchange    D. hide

4.What does the latest research indicate according to the passage?

A. Sleeping sickness is a blood disease.

B. Skin is more suitable for the parasite to grow.

C. Sleeping sickness can be spread with no signs.

D. Parasites in the skin caused the 1970s infection.

Answer

1.C

2.D

3.A

4.D

【解析】本文是一篇说明文。讲述了人们被采采蝇叮咬后会导致昏睡病，昏睡病一直被认为是一种血液疾病，因以前研究发现采采蝇寄生在人体血液中；但在最近的一项研究中发现，这种寄生虫还可以在皮肤和脂肪中寄生，这就意味着一个人没有症状，但仍然可以传播它。这也解释了20世纪70年代以来为什么这种疾病会在以前被清除的地区出现。

1.细节理解题。通过全文内容以及第三段第一句It is worth noting that sleeping sickness is no longer as deadly as it once was.可知，被采采蝇叮咬的危险是可能会带来死亡，虽然由采采蝇叮咬造成的昏睡病没有以前致命了。故选C。

2.细节理解题。根据第三段中“By the 1960s the disease was considered "under control" and had reached very low numbers, making its spread more difficult.（到了20世纪60年代，这种疾病被认为“处于控制之下”，并且已经达到了很低的数量，使其传播更加困难。）”可知，它在20世纪60年代完全控制住了。故选D。

3.词义猜测题。根据第一段中“That means a person can have no symptoms but still both harbor the disease and spread it.（这意味着一个人可能没有任何症状，但仍然__________疾病并传播它）”可知，harbor意为“怀有，携带”。A符合题意，故选A。

4.细节理解题。根据最后一段中“in a recent study found that the parasite can stay in the skin and fat, as well as in the blood. There may even be a higher density（密度）of the parasite in the skin than in the blood.（在最近的一项研究中发现，这种寄生虫可以待在皮肤和脂肪里，以及血液中，甚至可能在皮肤里的寄生虫密度高于血液中的。）”可知，最新的研究发现了1970年代的感染是由寄生在皮肤里的采采蝇引起的。故选D。