A Methadone is an effective way to treat a hard heroin addict.
B Methadone is not a correct way to treat a heroin addict.
C Hospitalization together with methadone can work effectively with a heroin addict.
D Methadone and heroin are equally effective in treating a heroin addict
A strong measures have been taken by the government to prevent global warming.
B to reduce carbon emissions is all impossible mission.
C despite the difficulty,scientists have some options to prevent global warming.
D actions suggested by scientists will never be realized
Scientists resist talking about their options because they don't want people to
A know what they are doing.
B feel their efforts are useless.
C think the problem has been solved.
D see the real problem.