The electric shaver______before it can be used.A．must repairB．should be in repairC．has to

A ground can be defined as an electrical connection between the wiring of a motor and its_____.

I caught a __________ of the taxi before it disap

It can be inferred from Paragraph Five that______.A．the ESFI inspects household electrical

The _____ compressor and its electrical motor are entirely housed in a gas-tight casing.A.

It was well known that Thomas Edison _____ the electric lamp.A.discoveredB.inventedC.fo

Edison failed _____ times before he succeeded in producing the first electric lamp .