My study in junior high school is coming to an end. It's time ____us_______.
A:for, graduate
B:to, to graduate
C:for, to graduate
D:to, graduating.
如图所示,三个等势面上有a、b、c、d四点,若将一正电荷由c经a移到d点,电场力做正功W1;若由c经b移到d点,电场力做正功W2,则W1与W2,c、d两点电势φc、φd关系为( )
“夜雨”点明____,“诗意”让你有一种____,____,____的感觉。
小船在静水中的速度为r.若小船过河时箭头始终与岸垂直,水流速度增大后( )