单项选择题
The hydrocarbons they do emit are less likely to（）ozone.
A.general B.generation C.generate D.generous
单项选择题 Ethanol is commonly used as a gasoline supplement, but it is currently about（）methanol.
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.
