The country has been ______ war with its neighbor for almost ten years.

A．in

B．on

C．at

D．during

李明在家中清洗带油污的餐具，用下列哪种方法能把餐具清洗得最干净( )

A．在冷水中加几滴洗涤剂

B．在热水中加几滴洗涤剂

C．只用热水

D．只用冷水