下列做法不正确的是（　　）

A．用食盐区分软水和硬水

B．用带火星的木条鉴别氧气和空气

C．用燃烧的方法鉴别羊毛和棉线

D．用熟石灰鉴别铵态氮肥和钾肥

—  I hear that you have made a new market plan.  

— Yes, but what puzzles me now is how to ______the plan. [ ]

A. carry out          

B. pull out        

C. put out        

D. work out