— If I work hard at my lessons from now on. Can I do well in them?
— Sure. .
A:All rivers run into sea
B:Every day is not Sunday
C:Better late than never
D:Many hands make light work
对质量守恒定律的正确理解是( )
在室温下,100ml 0.1mol/L的醋酸溶液中,欲使其溶液的pH值减小,但又要使醋酸电离程度减少,应采取( )
复数z1、z2在复平面内分别对应点A、B,z1=3+4i,将点A绕原点O逆时针旋转90°得到点B,则z2-=( )