We don’t permit _____in the classroom; that is to say, students aren’t  permitted _____in the classroom.[ ]

A. to smoke; to smoke          

B. smoking; smoking  

C. smoking; to smoke          

D. to smoke; smoking

品质是指商品所具有的内在质量，包括各种性能指标，具体有规格、型号、等级、花色、设备是否成套设备等。