机电工程英语(复习)机电工程英语(复习题).docVIP

一、Place a “T” before sentences that are true and an “F” before those that are false ( T )1、A worm gear is sometimes used in machines, it has low friction that can save considerable power. ( T)2、In a cam mechanism, when the cam turns through one motion cycle, the follower executes a series of event consisting of rises, dwells and returns. ( T)3、Integrated circuit is built on a semiconductor substrate, usually one of multi-crystal silicon. ( T )4、Krichhoff’s voltage law states that the sum of the potential drops around a loop in a circuit must be zero. ( F )5、Electrons and protons are said to have the same positive charges. ( T )6、If a sinusoidally varying voltage source is connected across the capacitor, it can be shown that the voltage across the capacitor lags the current by in phase, meaning that the voltage peaks occur 1/4 of an oscillation period later in time relative to the current peaks. ( T )7、 The advance of water as a pressure medium took a double hits near the turn of 20th century: one is the electric power control and the other is the oil hydraulic control system ( F )8、An ON-delay timer is enabled when its rung is false. ( T )9、Water hydraulics is a wholly new technology. ( F )10、Acceleration is the rate of change of displacement. ( F )11、Gears can change the rate of rotation of a machinery shaft but can not change rotary motion to linear motion. ( T )12、Krichhoff’s current law states that the sum of the current entering and existing a node must be zero. ( T )13、Integrated circuit is built on a semiconductor substrate, usually one of multi-crystal silicon. ( T )14、The first integrated circuits were created in the late 1950s in response to a demand from military for miniaturized electronics to be used in missile control systems. ( F )15、Electrons and protons are said to have the same positive charges. ( F )16、An OFF-delay timer is enabled when its rung is true. ( T )17、A robot may act under the direct control of a human or autonomously under