It just isn't fair ________ I was working as a cleaner last month; my friends were on a visit to Dalian.( 2012·湖北八校联考)

A．whenever

B．though

C．for

D．while

餐用具清洗消毒的目的是（）。

A.去除表面的污垢

B.杀灭致病性微生物

C.杀灭所有的微生物

D.去除餐用具表面的污垢和有害微生物