Millions of teenagers are in danger of putting their health at risk by getting hooked on e-cigarettes，experts warn．Leading health researchers say they are"very concerned"by the growing number of youngsters trying the devices．
Ecigarettes have been marketed as a healthier alternative to smoking conventional cigarettes．But previous research shows ecigarettes generate poisonous chemicals similar to those found in tobacco and may harm the lungs and immune system．
Worryingly，researchers at Liverpool University discovered 16% of teenagers who have used ecigarettes had never previously smoked．The experts also found ecigarettes were"strongly related"to drinking among teenagers．Study author Prof．Mark Bellis said，"Our research suggests that we should be very concerned about teenagers accessing ecigarettes．While debate on ecigarettes has focused largely on whether or not they act as a gateway to tobacco cigarette use，ecigarettes themselves contain a highly addictive drug that may have more serious and longer lasting impacts on children because their brains are still developing．"
Researchers surveyed 16，000students aged 14to 17in the North West of England and asked them about their alcohol and tobacco use．They found that one in five answered yes to the question："Have you ever bought or tried electronic cigarettes？"More males than females said they had．
Of the teenagers that had accessed ecigarettes，16% had never smoked，23% had tried smoking，12% only smoked when drinking，and 14% were exsmokers．The research also found teenagers who drank alcohol were significantly more likely to have accessed ecigarettes than nondrinkers．
Among those who had never smoked，it was found that those who regularly have excessive（过多的）drinking were four times more likely to access ecigarettes than those who never drink．In all of those that drink，regardless of smoking status，ecigarette access was associated with excessive drinking and involvement with violence after drinking．The researchers said their findings suggest that teenagers who use ecigarettes are most susceptible to other forms of substance use and risktaking behaviors．



How have ecigarettes been promoted in the market？ ______

A. As a healthier substitute for traditional cigarettes．
B. As a device meeting the mental needs of smokers．
C. As a product preventing smokers from using tobacco products．
D. As a new device promoted among youngsters．

What do we learn from the survey made in the North West of England？ ______

A. E-cigarettes are now widely available and heavily promoted．
B. Ecigarette access is linked to excessive drinking and violence after it．
C. Teenagers are very knowledgeable about alcohol and tobacco use．
D. The number of adult cigarette smokers is dropping at present．

Which of the following can replace the underlined words"susceptible to"in the last paragraph？ ______

A. greatly interested in
B. commonly accustomed to
C. deeply disappointed at
D. easily influenced by

What's the main idea of the passage？ ______

A. Experts are concerned about excessive drinking in teenagers．
B. The harm of the ecigarettes is greater than that of alcohol．
C. Teenagers are in danger of risking their health on ecigarettes．
D. Researchers are aware of smokerelated health harm．