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(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 increasing8 c8 a1 b* Q* j% ^& b
B.are increasing' ?4 `" ]) S8 B6 @$ C4 i
C.has been increasing
1 ]0 E4 I4 O) B. R9 f! g9 h2 @
D.have been increasing$ U* [# j- ] W6 E! F

答案C

解析