1. (2023高三下·汕头模拟) 阅读理解

The human brain is the most complex and poorly understood biological structure known to man. Our human brain is relatively large for our body size and wrinkled in comparison to other animals' brains. Across species, brain size and wrinkle number is related to intelligence.

University of Copenhagen researchers have made an incredible discovery seeking to learn more about the mammalian（哺乳动物的）brain. A vital enzyme（酶）, a special material, allows brain signals to be transmitted or transported. The enzyme is randomly turning on and off, even taking hours-long "breaks from work." These discoverie8 could have a significant impact on our understanding of the brain and the development of medicines. The discovery is featured on the cover of Nature.

Millions of neurons (神经元) are constantly communicating with one another, shaping thoughts and memories and allowing us to move our bodies at will. Neurotransmitters are transported from one neuron to another by a unique enzyme when two neurons meet to exchange a message.

This process is necessary for neuronal communication as well as the survival of all complex organisms (extremely small living things). Until now, researchers all over the world assumed that these enzymes were constantly active, transmitting vital signals. However, this is not the case.

It is almost impossible to understand that the extremely critical process of loading neurotransmitters in containers is carried out by only one cell per container. Especially when we find that 40% of the time these cells are switched off.

Using a new method, researchers from the Department of Chemistry at the University of Copenhagen closely examined the enzyme and discovered that its activity switches on and off at random periods of time, contradicting our previous understanding.

"Contrary to popular belief, and unlike many other proteins, these enzymes could stop working for minutes to hours. Still, the brains of humans and other mammals are miraculously able to function," says Professor Dimitrios Stamou, who led the study from the research center at the University of Copenhagen's Department of Chemistry.

1. （1） What is implied in the second paragraph?

   A . The enzyme is continuously turning on and off. B . Enzyme does not affect the transmission of brain signals. C . No enzyme has been found in the mammalian brain so far. D . Scientists used to think the special enzyme does not take a break.
3. （2） How could we move our bodies as we like?

   A . The communication between neurons happens without stop. B . We shape our thoughts though we may not have good memories. C . The newly found unique enzyme is at the most time switched off. D . Neurotransmitters transport a unique enzyme from one neuron to another.
5. （3） Why do the scientists think the discovery unbelievable?

   A . There is enzyme in mammalian brains. B . Mammalian brains function as human's. C . One cell can have such an important function. D . 40% of the critical cells are actually switched off.
7. （4） What can be the best title for the passage?

   A . A Surprising Significant Finding about Mammalian Brains B . A Very Important Research Led by Professor Dimittrios Stamou C . Researches on Brains of Animals Being Carried out By Scientists D . A Completely New Method Employed by the Department of Chemistry