①对于任意的x∈R,都有f(x)=cos (2x﹣ 2π3 );
②对于任意的x∈in R,都有f(x+ π2 )=f(x﹣ π2 );
③对于任意的x∈R,都有f( π3 ﹣x)=f( π3 +x).
其中,全部正确结论的序号是____.
—I have won the first prize in the speaking competition.