2. What was scientists‘ understanding of cryptic species？
A They occurred in equal numbers in all biogeographical regions.
B They were mostly found in insects find reptiles.
C They were likely to be in tropical rather than temperate regions.
D Both B and C.
3. Do scientists know how many cryptic species exist？
A Not yet.
B Yes，they do.
C They will know the answer in another one or two years;
D They will never know the answer.
4. Which of the following about the African bush elephant and the African elephant is true？
A The WCU are interbreeding those elephants.
B They are interbreeding species.
C They are two genetically distant species.
D They depend on each other for survival.
5. People were confused in their attempts to control malaria in Europe in the early1900s，because scientists
A identified only one mosquito species instead of six species.
B thought only three mosquito species transmitted disease.
C thought there was only one mosquito species.
D did not know what species was being studied.
答案与题解：
1. D 短文的第一段第二句的大意是，研究结果为广泛的研究领域提供启示，包括生物多样性研究，还能帮助我们理解传染疾病及其演变。所以，选项A、B、C都是正确的，它们不是答案。选项D的“适者生存”的内容文章中没有提及，因此是本题的答案。
2. D 短文的第二段第二句描述的是科学家目前的研究结果，第三段描述的是科学家在这之前对于cryptic species的理解。本题用的是过去式，问的是过去的状况，因此，答案在第三段中，B和C是答案，所以D是正确选择。
3. A 第三段和第五段提供了答案。第三段的倒数第二句中的Until.……no one will know just how many cryptic species exist.其意思就是人们目前还不了解。第五段的最后一句也说明了研究者目前对此尚未了解。
4. C 答案在第六段中。该段举了非洲大象为例，说明什么是cryptic species.第六段的句子“A 2001 study found the elephants were actually two genetically distinct，non- interbreeding spemes”是选择C的依据。选项A不对，the WCU并没有杂交繁殖这两种象。选项B不对，短文说这两种象是非杂交物种。选项D的内容短文中找不到。
5. A 短文最后一段告诉我们，由于对蚊子种类不了解，20世纪初期疟疾曾肆虐欧洲，最终，科学家才了解到蚊子这一物种不是由一个种类而是由六个种类组成。所以，应该选择A.