填空题
以下是某个窗体的模块代码，请分析单击窗体后程序运行至"*"号位置时变量X、Y和Z的值分别是{{U}} 【15】 {{/U}}。
DIM X AS INTEGER
DIM Y AS INTEGER
PRIVATE SUB FORM_CLICK()
DIM X AS INTEGER
X=1
Y=1
CALL AA(Y+1)
Z=BB(X)
'* * * * * * *
MSGBOX "X="&X&"/Y="&Y&"/Z="&Z
END SUB
PRIVATE SUB AA(BYVAL Z AS INTEGER)
Y=Z+X
Z=X+Y
END SUB
PRIVATE FUNCTION BB(BYREF Y AS INTEGER
Y=Y+1
BB=X+Y
END FUNCTION