加入NaOH溶液后,下列各溶液中哪种离子数目会减少( )
A:CO32﹣
B:K+
C:SO42﹣
D:H+
实验方案中一般只设一个变量因素,每个变量因素应设置对照,下列哪一项不是一组变量的因素( )
A: What can you see? B: I can see two____.A: What colour are they? B: They're____.