| 单词 | dial |
| 释义 | dial 1. A face, usually in the form of a disk, upon which some measurement is registered in graduations, and to which a pointer indicates a specific value. An analog clock or watch has a dial with 12 major graduations (hours) and 60 minor graduations (minutes and seconds). The second, minute, and hour hands sweep around the dial in a carefully synchronized manner. 2. A device, usually in the form of a disk, that is manually rotated to make electrical connections or to control the operation of a machine. 3. In telephone systems, a disk with holes in it that correspond to numbers 0 through 9 and that is mounted on a telephone set.The user places a call by addressing another telephone set identified by a sequence of numbers. In a simplified example, the caller sticks his finger in the hole associated with the first number in the sequence and rotates the dial until it reaches a hard stop and then releases it.As the dial returns to the starting position, it makes and breaks electrical contacts and sends a sequence of electrical pulses across a link to a switch.The switch counts the pulses and stores the number.When all numbers in the sequence have been dialed, the switch sets up the connection between the telephone sets and the conversation ensues. Dial pulse telephone sets are considered primitive today. Most telephone sets have keypads that generate either tones or digital signals. However, people still talk about dialing a telephone number. |
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