A、Because they want to see if biochemical changes can increase immunity. B、Because they want to see the long-term effects of sin

This isn’t a typical choir practice. And it’s not held in a traditional practice space. These singers are all dealing with cancer, theirs or a loved one’s. Rosie Dow, who leads the choir groups at Tenovus Cancer Care in the UK said, "There are people in our choirs who are undergoing treatment right now. There are some people who are waiting for treatment. "
    Virtually, chorus members have said that singing loudly makes them feel good. But Dow and her colleagues wanted to see if that psychological effect might translate to a biological effect. So they selected five choir groups in Wales—with a total of 193 singers—and took samples both before and after an hour of singing. They found that singers had significantly lower levels of the stress hormone after the session than they’d had prior to choir, along with an increase in proteins called cell genes—which the researchers say might suggest a boost in immune activity.
    It’s still not clear whether these biochemical changes translate to any better outcome for patients. And choir practice is in addition to—not instead of—conventional treatment. "Of course we wouldn’t recommend it as an alternative to surgery or any of the other conventional cancer treatments, but in terms of people’s mental health, this might be a good complement to the treatment that they’re having. "
    Next up, the researchers will conduct a follow-up study at the biggest cancer centre in the UK to see if these biological changes hold up over the long term. After all, singing is certainly a cheap treatment.
    Questions 9 to 11 are based on the passage you have just heard.
    9.Who are the members in this choir?
    10. What did Dow and her colleagues find in their study?
    11.Why will the researchers carry out a follow-up study?