From the earliest times there are records of dolphins(海豚) helping and caring for men. Although they can even kill sharks, they have never been known to attack a human being,rather they have helped men in difficulty on the sea. Dolphins' brains are 30 percent larger than those of people, and are equally complex. During experiments dolphins have learnt to perform tasks that require logical reasoning, so their intelligence is unquestionable.Furthermore, fossil evidence reveals that they have had their larger brains for thirty million years, compared to around a million years for man.

The dolphin ancestors lived upon the land, and dolphins are mammals(哺乳动物) like us, they feed their babies on milk, and breathe air like us. They appear to care for each other, for example if a dolphin is ill, its companions will help it up to the air so that it can breathe. The sounds they make also appear to be some kind of communication.

It seems that we have discovered an animal that may be close to us in intelligence, and furthermore one that is friendly, co-operative,and which has emotions similar to our own. How do we treat these animals? So far man has killed six million dolphins, and every year tens of thousands more are killed.

26. Which of the following statements best expresses the main idea of the passage?

A.Dolphins are human beings' best friends.

B.Dolphins have larger brains than that of human beings.

C.Dolphins are as clever as human beings.

D.Dolphins are quite close to human beings in many ways.

答案： D

[解析]此题是要旨题，提问的是文章的中心大意。就自学考试而言，文章或段落的主旨通常以主题句的形式出现。那么如何辨别主题句呢?文章的主题句一般是文章的第一句，但有时也出现在文章的中部或甚至文章尾部。本篇文章的主题句即出现在第三自然段的开头。在这篇文章中，作者在第一自然段中谈到了海豚的智力跟人类的十分相似，在第二自然段中又谈到海豚的生活方式跟人类的也有很多相似之处。故D是正确答案。

27.We can learn from the first paragraph that ______ ?

A.Dolphins have smaller brains than that of men.

B.Dolphins have had their intelligence not as long as men.

C.Dolphins have had their intelligence thirty times as long as men.

D.Dolphins are much more clever than men.

答案：C

[解析]这是一个细节理解题，考的是第一自然段中的一个细节。第一自然段的前部分讲到“Dolphins’brains are 30 percent larger than those of people, and are equally complex.”(海豚的大脑比人类的大30%，而且跟人类大脑的复杂程度差不多)，故A)，D)均不正确。第一段最后一句话讲到“fossil(化石)evidence reveals that they have had their larger brains for thirty million years, compared to around a million years for man.”(从海豚的化石证据显示，他们拥有这么大型的头脑已有3千万年的历史了，而我们人类的头脑只有一百万年的历史。)C为正确答案。

28.It can be inferred from the passage that_____.

A.Dolphins' brains are much larger and more complicated than that of men.

B.Dolphins are able to display the ability of reasoning.

C.Dolphins can play music like human beings.

D.Dolphins often held their babies up to breathe fresh air.

答案：B

[解析]从inferred一词得知此题是推理题。此题的推理依据是文章第一段，“During experiments dolphins have learnt to perform tasks that require logical reasoning”(在实验过程中，海豚们学会了做那些需要逻辑推理才能完成的工作)。由此我们可以判断出，海豚是能够有推理能力的，故选B。

29.Which of the following is true according to the passage?

A.Though dolphin is a kind of fish, it can breathe air like us.

B.Dolphins often kill sharks for food.

C.Dolphins probably communicate with each other through a kind of sound.

D.Dolphins have formed their own groups and they help only the members in the same group.

答案：C

[解析]这是一个细节理解题，从第二段的最后一句可以得知“The sounds they make also appear to be some kind of communication.”(他们发出的声音似乎就是一种交流的方式)，故应选C。

30.What would the next paragraph probably talk about?

A.Why dolphins are as intelligent as human beings.

B.How the dolphins help and care men in modern times.

C.How the dolphins were killed for commercial purposes and what we should do to protect them

D.What more discoveries scientists have made about dolphins.