Abstract: A storage device stores failures and lessons. A processor accepts input of text serving as a question sentence in a multiple-choice quiz, computes an evaluation value for a consistency between the text and each of lessons stored in the storage device, and determines one lesson to serve as a correct option in the multiple-choice quiz and at least one lesson to serve as an incorrect option in the multiple-choice quiz, based on the evaluation value for each of the plurality of lessons computed in the computing operation.

Abstract: LSI chips are divided into a first chip and a plurality of second chips, and each of the first and second chips has a frequency divider for deriving a lower-frequency output clock signal from a higher-frequency input clock signal. A higher-frequency input clock signal is supplied to the first chip from an external clock source to produce a lower-frequency output clock signal. One of the second chips is selected by a chip selector and its clock output is applied to a phase comparator for comparison with the clock output of the first chip for generating a phase difference signal in response to a phase difference between the compared output clock signals. Gate circuits are enabled in the absence of the phase difference signal to supply the input clock signal to all of the second chips. The chip selector is shifted to the next one of the second chips in response to a chip selection signal in the absence of the phase difference signal.