What is the standard for giving a jury a full and complete explanation of the law in a jury trial?

"[S]ection 1138 . . . provides that when the jury 'desire to be informed on any point of law arising in the case, . . . the information required must be given . . . .' The 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 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.)