由题意可知,5/13*8/17+9/13*5/17=5/13*8/17+5/13*9/17=5/13*(8/17+9/17)=5/13。
5/13×8/17+9/13×5/17=5/13×(8/17+9/17)=5/13×1=5/13
VB好尴尬呀,?。?。!