A、28% B、22% C、25% D、21% B简单数字计算。

The University of Michigan carries out a survey of the drug habits among young people every year. And this year it’s concluded that teenage drug use is rapidly getting worse. 25 percent of teenagers surveyed said they’d used an illegal drug at some time in their lives, an increase of 3 percent from the figures for 1993. Marijuana use is climbing back towards levels not seen since the late 1970s. And today’s marijuana is up to ten times more potent than in the past. Cocaine use, which levelled off in the early 1990s, is also making a comeback among 13- to 15-year-olds. And LSD, which had dropped considerably in the 1980s, is also on the rise. Officials involved in the survey say the results indicate that young people no longer see drugs as dangerous; instead, the researchers say, they are viewed as glamorous or trendy. The Health Secretary said it was time to Sound the alarm. And the Secretary calls for a powerful anti-drug message to be sent to children, with parents leading the way.