Many psychologists in the early twentieth century believed that humans use only 10 percent of their brains, and even the great Albert Einstein once wrote that most people use only a small portion of the grey matter between their ears. It’s a theory that has often been put forward in television documentaries; magazines, advertisements and books over the past century.
But nearly all scientists now agree the 10 percent theory is completely unfounded. In fact, they question how this figure was ever arrived at in the first place and what areas of the brain are supposed to be unneeded. The theory supposes that if 90 percent of the brain were removed, a person would Still be able to function normally, while in reality it is known that damage to even a small area of the brain can result in extremely serious physical injury different activities and that many areas of the brain are used at the same time for some complex activities or thought processes.
Throughout the course of one day, most .areas of the brain are active at some time, even during sleep. The 10 percent theory suggests that certain areas o’ the brain are not used, but scans slow activities throughout the entire brain and not in any separate part. The final argument against the 10 percent theory is the fact that doctors carefully map the brain before removing brain cancers so that they don’t affect other essential areas.
From an evolutionary point of view, it’s highly unlikely butt our comparatively larger brains would have evolved from our ancestors if the extra areas were not needed. In fact, there is absolutely no evidence support the 10 percent theory.
How did the 10 percent theory get such widespread popularity?

A．It was promoted in various types of copular media.

B．Albert Einstein argued strongly in support.

C．It was proven in scientific research.

D．Few people could prove it wrong.

The underlined word "unfounded" is chest in meaning to _________.

A．undiscovered

B．unproven

C．unknown

D．unnecessary

Which of the following is true according to the writer?

A．We use less than 10% of our brains.

B．Most brain disorders affect the same part of the brain.

C．The brain is less active during times of sleep.

D．The 10 percent theory does not make evolutionary sense.

What can we infer from the passage?

A．People today use more of their brain than in the past.

B．Scientific opinion about the topic of brain use is equally divided.

C．Our understanding of the brain has changed greatly in the past decades.

D．Modern scientists have a complete picture of how the brain works.

What is the main purpose of the passage?

A．To present two sides of brain theory.

B．To criticize the 10 percent theory.

C．To explain how brain works.

D．To describe the history of brain research.