A:小球对圆管的内、外壁均无压力
B:小球对圆管的外壁压力等于 mg2
C:小球对圆管的内壁压力等于 mg2
D:小球对圆管的内壁压力等于mg
It was in his ____ (forty)that Liu Cixin completed his famous novel Three bodies.
已知某温度下,0.1 mol·L-1NaHB溶液中,C(H+)>c(OH-),则下列各关系式一定正确的是
计算:1﹣(﹣13)=( )