问题补充:
(·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:
A. is increasing
B. are increasing
(答案→)C. has been increasing
D. have been increasing
解析: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。