20．Tell John not to leave the house unless he　　　 that the lights　　　 .

A．will make sure，turn off

B．makes sure，are turned off

C．will make sure，will turn off

D．makes sure，will be turned off

19．Mrs．Brown is so　　　 about her housework that few servants Want to work for her．

A．skillful　　 B．neat 　C．particular　 　D．special