任务型阅读

　　For a long time, scientists didn’t study animal thinking．Most of them did not believe that animals could think．They thought humans were the only thinking animals．

　　Now more scientists are studying this subject．But it’s very hard to prove things that no one can see or measure．So some scientists decided to take a look at brains．

　　Is bigger better?No．Cow brains are bigger than dog brains, but that doesn’t make cows smarter than dogs．And squirrels have some of the biggest brains of all for their body size．But squirrels aren’t even close to being the smartest animals in the world．So the size of a brain may give some clues(线索)about brain power, but it doesn’t prove anything．

　　Other scientists study thinking by ________ how animals solve problems．They watch animals in the wild or do thinking tests in a lab．

　　For example, the scientist might put some food just out of an animal’s reach．One kind of animal may grab a stick and use it to slide the food over．Another kind might not be able to figure out a way to get the food．Some scientists think animals that have lots of problems to solve must be smarter than animals with simple lives．Scientists also study certain kinds of behaviour for clues about thinking．They watch for three things：whether animals use tools, how they act with each other, and how they communicate．

1．“This subject” in Paragraph 2 refers to ________．

2．The underlined word “smarter” means ________ in English．(限填一词)

3．What have scientists learned from studying the size of animals’ brains?

________________________________

4．Complete the sentence with just one word：Other scientists study thinking by ________ how animals solve problems．(限填一词)

5．Scientists study such animals’ behavior as whether animals use tools, how they act with each other and ________ as well．