下列哪些是消化道的癌前病变()
A.口腔黏膜白斑
B.慢性萎缩性胃炎
C.结肠多发性息肉
D.慢性胃溃疡
E.慢性溃疡型结肠炎
参考答案:A, B, C, E
---Were your parents at home last night?
---No. We ________ went to Grandma’s birthday party.
A.both
B.all
C.none
D.neither
如图所示,质地均匀的实心圆柱体A、B叠放在水平地面上,已知他们的密度之比ρA:ρB=1:3,底面积之比SA:SB=4:3,A对B的压强和B对地面的压强之比PA:PB=1:2,则他们的高度之比hA:hB为
A.9:4
B.3:2
C.3:1
D.9:2