钢管外防腐层施工,属于规范规定必须检验的项目有()。
A.水泥砂浆抗压强度
B.外防腐层厚度
C.电火花捡漏
D.粘结力
E.内防腐层厚度
参考答案:B, C, D
We have sent some books to the children in that village. However, they still need ______.
A.more
B.much
C.many
D.most
混凝土外加剂中氯离子含量测定所用试剂中氮气纯度不小于()%。