题干
Paper produced every year is the world's production of vehicles.
A：the three times weight of
B：three times the weight of
C：as three times heavy a
D：three times as heavier a
答案(点此获取答案解析）
B
的烷烃有九种，其中仅能由一种单烯烃加氢而制得的有（ ）
