在英语句子“Wish you success!”（祝你成功！）中任选一个字母，这个字母为“s”的概率为( )
The girl or her friends____ to meet you at the station tomorrow. [ ]
A. is
B. are
C. were
D. have
A．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G
B．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为G
C．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G
D．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为G
G
G