【单选题】下列化合物中哪一个不产生红外光谱( )。
【单选题】Many governments didn't launch anti-smoking campaigns because ______.
A.
tobacco taxes take up a large part of their revenue
B.
they are unusually subject to cigarette advertising
C.
they don't think tobacco can do harm to people's health
D.
they are innocent of the link between tobacco and disease
【单选题】引起器官移植排斥反应堆抗原的是______。
【简答题】Campaigns began in the early 1980s, when people ______ the negative effects
of CO 2 emission.A. realize B. realized C. have realized D. had realized
【单选题】Campaigns began in the early 1980s, when people ______ the negative effects of CO 2 emission.