题目内容：

B

You carry a 1.3 kg mass of fatty material in your head that controls everything you will ever do. This fantastic control center lets you think, learn, create, and feel emotions. It also controls everything your body does. What is this amazing machine? It’s your brain — a structure so amazing that the famous scientist James Watson called it ＂the most complex thing we have yet discovered in our universe＂.

Imagine your kitten jumped onto the kitchen counter, and was about to step onto a hot stove. You would have only seconds to act. In situations like this, your brain reads the signals from your eyes and quickly calculates when, where and at what speed you need to run to save her. Then it tells your muscles to move. No computer can match your brain’s great ability to download, process, and react to the flood of information from your eyes, ears and other sensory organs.

If a bee lands on your foot, sensory neurons(神经元) in your skin send this information to your brain at a speed of more than 240 kilometers per hour. Your brain then uses motor neurons to send a message back to your foot: Shake the bee off quickly! Motor neurons can send this information at more than 320 kilometers per hour!

Your brain contains about 100 billion tiny cells: neurons — it would take you more than 3,000 years if you tried to count them all. Whenever you dream, laugh, think, see or move, tiny chemical and electrical signals are racing between these neurons along billions of tiny neuron pathways. Believe it or not, the activity in your brain never stops. Countless messages fly around inside it every second, like a super-fast game of table tennis. Your neurons create and send more messages than all the phones in the entire world. And although a single neuron generates only a tiny amount of electricity, all your neurons together can generate enough electricity to power a light bulb.

1.By ＂the most complex thing＂, James Watson means __________.

A. a supercomputer         B. the universe

C. human brains          D. our emotions

2.Which of the following statements is true according to the 2nd and 3rd paragraph?

A. Brains can download more information than any computer.

B. The kitten plays an important role in testing human brain power.

C. Motor neurons in human brains serve to send countless messages.

D. Your brains can use neurons to send messages back faster than bees’.

3. The author mentions ＂to power light bulbs＂ (Para. 4) to show __________.

A. neurons can send lots of messages

B. how many active tiny cells brains contain

C. how much electricity brains can generate

D. there is countless information in the brain

4.What is the main idea of the passage?

A. Powerful brain is a wonderful machine.

B. Brains work well in controlling body movements.

C. Brain is the most complex structure in the universe.

D. Human brains are composed of numerous neurons.