装车使用的篷布必须(),篷布绳齐全,标记、号码完整清晰。
A、附出厂证明
B、质量良好
C、附有合格证
D、经过批准
参考答案:B
下列离子方程式书写正确的是
A.鸡蛋壳和醋酸溶液的反应:CaCO3+2H+=Ca2++H2O+CO2↑
B.明矾水解的离子方程式:Al3++3H2OAl(OH)3↓+3H+
C.向稀硫酸加入少量Ba(OH)2溶液:2H++SO42-+Ba2++2OH-=BaSO4↓+2H2O
D.向NaAlO2溶液中通入过量CO2:2AlO2-+CO2+3H2O=2Al(OH)3↓+CO32-
Friendship helps us understand we are, we need each other and we can do for each other.
A.what; why; how
B.who; how; what
C.who; what; why
D.who; why; what