A:实验室中常用饱和食盐水除去Cl2中混有的HCl
B:银器长期放置,表面变暗
C:红棕色的NO2加压后颜色先变深再变浅
D:氨水中加酸,NH4+的浓度增大
— How do you like the regulations of our school?
— The regulations are strict with the students and they require that students _______ at least 90% of the lectures.
在探究“影响电磁铁磁性强弱的因素”实验中,小明制成简易电磁铁甲、乙,并设计了如图所示的电路.
测量苹果的密度: