Mary found _______extremely difficult to pass the examination.

A．Buy Nothing Day has become popular in the United States.
B．Restaurants have a tradition of donating food on holidays.
C．Gift shops are expected to be closed on Buy Nothing Day.
D．Children like the idea of Buy Nothing Day best.

A．The gasket should be cleaned thoroughly with cold water.
B．Mild detergent and hot water can best clean the cooker.
C．Soapy water will often damage the cooker.
D．Sand can be used to clean the cooker.