题目内容:
The traditional mechanical wristwatch uses a balance wheel and hairspring to keep time. In a digital watch these mechanical parts have been replaced by vibrating quartz crystal controlled by minute electronic circuits. The artificial quartz crystals used in digital watches are designed to vibrate up to 32768 cycles per second when the current from a battery is passed through them. These vibrations produce electric pulses. As the pulses travel through the electronic circuits of the microchip, their rate is gradually halved. The result creates a pulse rate of one per second. Each one –second pulse triggers the microchip to send signal to the digital display to advance the numerals by one second. The pulses are also used to control different functions such as the hour display, date and alarm signal. 1) The best title of this article is () A. Mechanical wristwatch. B. Digital Watch C. Electronic circuits D. Counter 2) How many times do the electronic circuits of the microchip halve when creating a pulse rate of one per second? () A. 10 B.15 C.13 D.12
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