已知反應(yīng)2NO(g)+Br2(g)=2NOBr(g)的反應(yīng)歷程是: (1)NO(g)+Br2(g)=NOBr2(g)快 (2)NOBr2(g)+NO(g)=2NOBr(g)慢 則該反應(yīng)對NO的級(jí)數(shù)為()。