下列属于天然牛黄商品特征的是（）
A、挂甲
B、断面有横纹
C、嚼之不粘牙
D、乌金衣
E、味微苦后甜
参考答案：A, C, D, E
矩阵512X512，显示野为25cm时，像素的大小为
A．0.2mm
B．0.3mm
C．0.4mm
D．0.5mm
E．0.8mm
Haier Company produced a new type of refrigerator of high quality and pretty appearance; its only ___is that it takes up too much room.
A．advantage
B．drawback
C．profit
D．mistake
