下列物质中含有氯离子的是( )
A.氯化氢
B.氯酸钾
C.氯气
D.氯化钙
氯化钙能电离出氯离子和钙离子,而氯酸钾中电离出钾离子和氯酸根离子,故选D.
图示结构的超静定次数为()。
A.2
B.3
C.4
D.5
Whenever new information is entered, it must be stored somewhere in the computer’s (70) . RAM only (71) the data temporarily. That is, all information stored in the RAM will disappear if you switch the computer off.
A.processor
B.keyboard
C.printer
D.memory