单选题
One day in 1963, a dolphin named Elvar and a famous astronomer, Carl Sagan，were playing a little game. The astronomer was visiting an institute which was looking into the way dolphins communicate with each other. Sagan was standing on the edge of one of the tanks where several of these friendly, highly intelligent creatures were kept. Elvar had just swum up alongside him and had turned on his back.
The dolphin wanted Sagan to scratch his stomach again, as the astronomer had done twice before. Elvar looked up at Sagan, waiting. Then, after a minute or so. the dolphin leapt up through the water and made a sound just like the word "more". The astonished astronomer went to the director of the institute and told him about the incident. "Oh, yes. That"s one of the words he knows," the director said, showing no surprise at all.
Dolphins have bigger brain in proportion to their body size than humans have, and it has been known for a long time that they can make a number of sounds. What is more, these sounds seem to have different functions, such as warning each other of danger. Sound travels much faster and much further in water than it does in air. That is why the parts of the brain that deal with sound are much better developed in dolphin than in humans. But can it be said that dolphins have a "language", in the real sense of the word? Scientists don"t agree on this.
A language is not just a collection of sounds, or even words. A language has a structure and what we call a grammar. The structure and grammar of a language help to give it meaning. For example, the two questions "Who loves Mary?" and "Who does Mary love?" mean very different things. If you stop to think about it, you will see that this difference doesn"t come from the words in the question but from the difference in structure. That is why the question "Can dolphins speak?" can"t be answered until we find out if dolphins not only make sounds but also arrange them in a grammatical order which affects their meaning.

单选题 The astronomer was not interested in the way dolphins communicate with each other.

单选题 The dolphin leapt up into the air because Sagan was too near the water.

单选题 Parts of the dolphin"s brain are particularly well developed to handle different kinds of sound.

单选题 Dolphins are the most useful animals to humans.

单选题 Dolphins travel faster in water than any other animals.

单选题 Some scientists believe that dolphins have a language of their own.

单选题 Sounds can be called a language only when they have a structure and a grammar.