题目内容：

PEOPLE who have had a painful experience may wish they could wipe the memory from their minds. Researchers at Johns Hopkins University, US, say that this may someday be possible.

A drug remains far off, but researchers have laid a foundation with their discovery that proteins can be removed from the brain’s fear center to cut memories forever.

Previous research had already shown that a special behavior therapy (治疗) could cut painful memories. But relapse (复发) was possible because the memory hadn’t necessarily disappeared.

By looking at that process, Richard Huganir and Roger Clem, two researchers from Johns Hopkins University, discovered a “window of vulnerability (脆弱的窗口)” when proteins are created. The proteins help signals travel within the brain as painful memories are made. Because the proteins are unstable, they can be easily removed with drugs or behavior therapy to cut memories.

Researchers used mice to find the window, but think the process would be the same in humans. They used electric shocks to make the mice fear a certain sound. The sound triggered (触发) the creation of the proteins, called calcium-permeable (钙通透性) AMPARS, which formed for a day or two in the fear centers of the mice’s brains.

The researchers are working on ways to reopen the window by recalling (唤醒) the painful memory and using drugs to remove the protein. They published their report online last month in Science Express.

Their research has drawn interest and concern from experts in mental healthcare.

Kate Farinholt, a mental health expert with the National Alliance on Mental Illness, Maryland, US, said many people suffering from a painful event might benefit from erasing a memory. “Erasing a memory and then everything bad built on that is an amazing idea, and I can see all sorts of potential ,” she said.

But there are a lot of unanswered questions, too.

“Completely deleting a memory is a little scary. How do you remove a memory without removing a part of someone’s life,” Farinholt said. “And is it best to do that, considering that people grow and learn from their experiences?”

1.What have researchers at Johns Hopkins University found recently?  

A. A new drug to erase painful memories from human brains.

B. A special behavior therapy to erase painful memories.

C. Removing certain proteins from the brain can wipe painful memories.

D. Erasing memory damages a patient’s brain functions.

2.What makes it possible to erase painful memories according to Paragraph 4? 

A. The way the brain cells are created.

B. The unstable character of the proteins in the brain.

C. The strength of the signals the proteins send.

D. The drugs that can stop the formation of memories.

3.Which of the following shows the stages of the process done on mice? 

a. removal of fear proteins            b. making mice fear a certain sound

c. fear proteins created in mice brains   d. making mice recall painful memories

A. a-b-c-d    B. d-a-c-b    C. b-c-d-a    D. c-b-d-a

4.What is Kate Farinholt’s opinion of the research? 

A. People may lose the chance to learn from their bad experiences.

B. The research will be a great breakthrough in treating painful memories.

C. People could suffer long-term memory loss.

D. People could forget happy memories as well.