阴离子初步试验的目的是( )。
A.排除试样中不存在的离子;
B.确定试样中存在的离子;
C.确定试样中可能存在的离子;
D.检验试样中肯定存在的离子。
参考答案:C
Read and order. 读句子排序。
( ) How are you?
( ) Tomorrow? What day is tomorrow?
( ) Fine, thank you. Would you like to play with me tomorrow?
( ) It's Monday
( ) OK. See you tomorrow!
( ) See you.
飞机客舱内起火,且有乘客时、应使用()内攻灭火。
A、直流水流
B、开花水流
C、雾状水流
D、密集水流