接触性泻药的作用包括()
A.粘膜透过性增加
B.改变血浆中电解质的水平
C.释放PG,使电解质分泌增加
D.肠内渗透压升高
E.直肠反射性蠕动增强
参考答案:A, C, E
—What would you wish to do if you were a college student again?
—That's very hard to say, but I wish I when I was a college student.
A.has not studied biology
B.did study biology
C.had studied biology
D.studied biology
复杂系统是指组成系统的要素比较多、结构比较复杂的系统。( )