问题
选择题
(2013·安徽省芜湖三校一模)A recent study has found that the number of smokers ________ sharply over the past five years.
A．is increasing
B．are increasing
C．has been increasing
D．have been increasing
答案
答案：C
选C 考查时态和主谓一致。句意：最近一项研究表明，在过去五年里，吸烟者人数急剧上升。the number of后接复数名词作主语，谓语动词则用第三人称单数；时间状语over the past five years表明用现在完成进行时。