有人能解释一下原因吗? 谢谢。
%let Mv=shoes;
%macro PRODUCT(Mv=bicycles);
%let Mv=clothes;
%mend;
%PRODUCT(Mv=tents)
%put Mv is &Mv;
*compare this;
%let a=cat;
%macro animal;
%let a=dog;
%mend;
%animal
%put a is &a;
answer:Mv is shoes,a is dog