下列运算正确的是( )
A:2x2•x3=2x5
B:(x﹣2)2=x2﹣4
C:x2+x3=x5
D:(x3)4=x7
Kate isn't happy because she lost her pet. Let's go to cheer her up.
一个物体在平衡力的作用下( )
某同学用分子的观点解释下列现象。其中错误的是( )