单项选择题
Ethanol is commonly used as a gasoline supplement, but it is currently about（）methanol.
A.twice as expensive as B.twice as more expensive as C.as twice more expensive as D.as twice expensive as
单项选择题 At a rough estimate,Nigeria is（）Great Britain.
单项选择题 There is a serious liability（）performance and fuel efficiency.
单项选择题 Although recent years have seen（）reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing.
