Animal thinking.
For a long time,scientists didn't study animal thinking.Most of them didn't 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 about brain power,but it doesn't prove anything.Other scientists study thinking by watching how animals solve problems,who watch animals in the wild or set up thinking tests in a lab.For example,a 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.
這是短文
1 For the body size,do dogs have smaller brains than squirrels?2 What have scientists learnt from taking a look at the size of animals' brains?3 How do other scientists study animal thinking?4 What are some certain kinds of behaviour for clues about thinking that scientists study?5Put the sentence "but it's very hard to prove things that no one see or measure."into Chinese.