(1)-y(3x-y)2 ;(2)-2ab
_______ left at the first crossing and then you can see the bookshop. [ ]
A.Turn
B.Take
C.Choose
D.Get
服盐类泻药引起腹泻的原因是()
A.肠黏膜分泌增多
B.肠腔内渗透压增高
C.肠黏膜吸收障碍
D.肠蠕动过快
E.肠腔内渗透压低