A、The people who drink during dinner. B、The disease caused by drinking. C、The cost of heavy alcohol use. D、The money spent on dr

A new study has found that excessive alcohol drinking costs Americans more than 220 billion dollars a year. That amount is equal to almost two dollars a drink. But study organizers believe the biggest costs come from a loss of worker productivity.
    Robert Brewer works for America’s Centers for Disease Control and Prevention, a public health agency. He helped to produce a report on the study.
    The researchers used findings from 2006 to examine different costs linked to heavy drinking. They looked at results from around the United States and found a lot of variation in different parts of the country.
    Alcohol related costs include health care, the cost of trying cases for drinking related crimes and property damage from road accidents. Robert Brewer says the biggest cost is lost productivity. Many people with a drinking problem have lower paying jobs. He says they may also be less productive when they are at work.
    " In addition to that, a number of people die of alcohol drinking, and many of those folks die in the prime of their life. So there is the personal tragedy there, but there is also a huge economic cost to somebody dying, for example, in an alcohol related motor vehicle crash at age 35. "
    The researchers were mainly concerned about the cost of heavy alcohol use. The study didn’t look at the effect on individuals who drink a glass of beer or wine with dinner. Mr. Brewer says the largest costs come from over drinking when people drink a lot of alcohol in a short period of time.
20.What has the new study found about excessive alcohol drinking?
21.What is the biggest cost of excessive alcohol drinking according to Robert Brewer?
22.What does the research mainly focus on?