【正确答案】
B
【答案解析】[听力原文] Morning, class. Today I've brought in a picture of the human brain, which we are going to look at and discuss in detail. The brain is like our command center for all our daily functions and allows us to cope with our environment. How we communicate with words, actions, thoughts, and feelings are all centered in the brain. Some researchers believe that the brain is so complex and mysterious that we will never be able to fully understand it. Some have even referred to it as a little black box like those found on a plane that contain all the critical and highly confidential information of the flight. It's easiest to think of the brain as three connected parts: the cerebrum, brainstem, and cerebellum. Let's start off with the brainstem, which is found at the bottom of the brain. The brainstem has an important role because it controls lots of critical functions including respiration, regulation of the heart rhythms, basic aspects of sound localization. Next, we'll look at the second largest part of the brain—the cerebellum. It is located at the lower back of the head and is attached to the brainstem. It is made up of two hemispheres and its functions are to control complex voluntary motor functions such as walking, balance and posture. The third and largest part of our brain is the cerebrum. Its associations are conscious thought, movement and sensations such as touch, vision, hearing, judgment, reasoning, problem solving, and emotions. The average weight of an adult human brain is anywhere between 1 and 1.5 kilograms. Some people say that we only use 10% of our brain, but this is just a myth. In fact, we use our entire brain. That being said, we can claim that most people only use a very small fraction of the cognitive potential of their brain. Different cultures have used several methods to improve their cognitive potential such as reading, education, puzzle solving and critical thinking. I hope this brief introduction to the brain helps you understand the brain and its different functions. Where is the brainstem located in the brain? 听力原文中提到Let's start off with the brainstem，which is found at the bottom of the brain. 明确指出脑干位于大脑的底部，故选B。