Which of the listed devices may be used as a digital device?

A．variable resistor

B．diode

C．strain gauge

D．thermistor

[单选题]Which of the units listed is used to combust waste in the engine room?A．BoilerB．IncineratorC．Generator

[单选题]Which of the following writing activities may be used to develop students′

[单选题]Which of the conditions listed will cause a refrigeration compressor to run constantly without simultaneously decreasing the temperature in the refrigerated space?( )A．Shortage of refrigerant oilB．Slight shortage of refrigerantC．Excessive condenser c

[单选题]Which of the listed factors will indicate the most about the ability of a fuel to ignite in a diesel engine?A．ViscosityB．Sulfur contentC．Pour pointD．Cetane number

[单选题]Which of the substances listed is satisfactorily removed from the fuel by a centrifugal oil purifier?（）A . ImpuritiesB . Lube oilC . GasolineD . Diesel fuel

[单选题]Which of the following devices is a common basic element with nearly all mechanical governors?A．Power pistonB．Control rackC．Weights acted on by centrifugal forceD．Isochronous（同步的）droop spring

[单选题]Which devices are instruments of interpretation and communication between humans and computers?A．main memoryB．input/output devicesC．CPUD．hard disk

[单选题]Which of the following devices is common to both mechanical and hydraulic governors?（）A . Direct linkage between the ball-head and fuel rackB . A servomotorC . A compensating deviceD . Flyweight

[单选题]Which of the following devices is a common basic element with nearly all mechanical governors?（）A . Power pistonB . Control rackC . Weights acted on by centrifugal forceD . Isochronous droop spring

[单选题]Which of the listed conditions can be considered as the single greatest cause of accidents?A．SpeedB．Excessive knowledge or skillC．Human errorD．Excitement