There were many ________ there.[ ]
A. backpacks
B. backpack
C. a backpack
答案:A
皮表颜色深红或青紫抚之碍手,压之不褪色者多为()
A.麻疹
B.白痦
C.水痘
D.发斑
E.湿疹
离心泵轴径为30--50mm,转速在1500r/min以下,轴与轴瓦间隙应为()。
A.0.075~0.160mm
B.0.08~0.2mm
C.0.2~0.1mm
D.0.06~0.19mm