Passage One
Questions 21 to 25 are based on the following passage.
If you start each day desperately wishing for an extra hour in bed, the following is likely to leave you feeling even more bad-tempered. Scientists have identified a "sleepless elite"- a small group of people for whom staying in bed longer is a waste of time.
Rather than being tired and bad-tempered losers, they are an energetic, outgoing and optimistic group who can happily and healthily get by on just four or five hours of sleep a night. And, they tend to be slim, able to hold down two jobs at the same time, and handle their extra-long days easily without needing coffee or catnaps (小睡).
Working out how the gene (基因) cuts sleep without any obvious impact on health could help in the design of drags that give us all a few extra hours in our day. The bad news is that while many of us get by on a few hours' sleep a night, just one to three people in 100 qualify to be part of the sleepless elite.
The research team is now calling for members of the lucky group to come forward to allow their DNA to be studied. Harvard University researcher Dr. Christopher Jones said: "My long-term goal is to learn enough someday so we can control the sleep mechanism without damaging our health. Everybody can use more waking hours, even if you just watch movies."
Many of those who have already volunteered share fascinating characteristics. They are cheerful, thinner than average, and seem to have a high tolerance for physical pain and psychological setbacks.
Dr. Christopher Jones told the New York Times: "Typically, at the end of along phone interview, they will admit they have been sending short text message sand surfing the Internet and doing word games at the same time, all on less than six hours of sleep."
23.The phrase "come forward" (para. 4) is closest in meaning to（ ）