What tone did the trial judge take when questioning an expert?

We cannot tell from the cold record what tone the trial judge took when questioning the expert or whether the questions were motivated by skepticism, curiosity, or both. But we cannot conclude that the questions were necessarily improper, and we have no reason to believe that the jury failed to follow the court's jury instruction that nothing the judge said or did were intended "to intimate or suggest what you [the jurors] should find to be the facts, or that I believe or disbelieve any witness. [] If anything I have done or said has seemed to so indicate, you will disregard it and form your own conclusion." (CALJIC No. 17.30; accord People v. Harris, supra, 37 Cal.4th at p. 350 [even though some of trial court's questions were "inappropriate," reviewing court must assume jurors followed instruction not to decide case based on what court said or did].)