男性,60岁,排便习惯改变,大便变细、混有粘液脓血1个月。便常规检查可见多数红细胞。首选应做哪项检查
A.肛门指检
B.下消化道造影
C.B超
D.钡灌肠
E.纤维结肠镜
参考答案:A
下列说法正确的是[ ]
A.强电解质溶液的导电性一定比弱电解质溶液的导电性强
B.BaSO4难溶于水,所以它是弱电解质
C.弱电解质溶液中电离出的离子和未电离的分子共存
D.共价化合物都是弱电解质
This is a very interesting book.I'll buy it,_____ . [ ]
A. how much may it cost
B. no matter how it may cost
C. however much it may cost
D. how may it cost