单项选择题
A.succeed B.proceed C.exceed D.excess
Although recent years have seen substantial reductions ...
单项选择题Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles（）.
A.have been steadily increasing B.has been steadily increased C.has been steadily increasing D.have been steadily increased
Vehicles（）only the simplest of the engine improvements ...
单项选择题Vehicles（）only the simplest of the engine improvements that methanol makes feasible would still contribute to an immediate lessening of urban air pollution.
A.corporate B.cooperating C.operating D.incorporating
Henry and Tom（）to the particles at the Trade Union ever...
单项选择题Henry and Tom（）to the particles at the Trade Union every Saturday.
A.used to go B.were used to go C.are used to go D.ues to go
