A:自行车轮胎做得凹凸不平是为了增大摩擦
B:自行车的坐垫很宽是为了减小压力
C:上坡前加紧用力蹬车是为了增大惯性
D:人对自行车的压力与地面对自行车的支持力是一对平衡力
读 《谈生命》,下面各项说法不正确的一项是( )
下列说法正确的是( )
____Six.
____I have computer class, PE and science.
____How many classes do you have on Wednesdays?
____Is it Wednesday today?
____What do you have in the afternoon?
____Yes, it is.