P18.窗体中有文本框Text1、Text2和Text3。运行,输入整数m和n(n>0),单机"计算"按钮Command1计算下列表的值 Sum=m-2(m+1)+3(m+2)-4(m+3)+.+(-1)n+1 n(m+n-1)n Text3给出结果。事件代码如下: Private Sub Commandl_Click() m=val(me!textl) n=val(me!text2) sum=0 For k=1 to n sum=sum+【】 Next k Me!text3=sum End 程序【】处应填写的语句是
A.
IIf(k Mod2=0,-k,k)*(m+k-1)
B.
IIf(k Mod2=0,k,-k)*(m+k-1)
C.
IIf(k Mod2>0,-k,k)*(m+k-1)
D.
IIf(k Mod2<0,k,-k)*(m+k-1)< p="">