A == 0or 1or 2
怎么写
if(a1=0||a1=1||a1=2,"第一个","第二个")
if(a='1'||a='2'||a='3',"","")
if(a=1,1if(a=2,2,if(a=3,3,null)))
if(or(a=0,a=1,a=2),"","")