What is the legal basis for appellant to argue that a jury should be asked for additional explanations in their instructions?

We reject this argument for two reasons. First, appellant failed to object on this ground in the court below. Therefore appellant has forfeited the right to raise the issue on appeal. (See People v. Roldan (2005) 35 Cal.4th 646, 729.)

Second, even if we were to ignore the procedural barrier, appellant's argument is unpersuasive. Penal Code section 1138 states that when the jury "desire[s] to be informed on any point of law arising in the case . . . the information required must be given . . . ." Our Supreme Court has interpreted this language to mean the trial court "has a primary duty to help the jury understand the legal principles it is asked to apply. [Citation.] This does not mean the court must always elaborate on the standard instructions. Where the original instructions are themselves full and complete, the court has discretion under section 1138 to determine what additional explanations are sufficient to satisfy the jury's request for information. [Citation.] Indeed, comments diverging from the standard [instructions] are often risky. [Citation.] . . . . But a court must do more than figuratively throw up its hands and tell the jury it cannot help. It must at least consider how it can best aid the jury. It should decide as to each jury question whether further explanation is desirable, or whether it should merely reiterate the instructions already given." (People v. Beardslee (1991) 53 Cal.3d 68, 97, original italics.)