During the period of ______ from oil heat to gas heat the furnace will have to be shut off

The trouble－free life of an engine indicates _____.A.the period of time during which no tr

During the period of prosperity, people regard the future ______.A．cautiouslyB．in a confid

In certain area, during certain period, the development of communication could ______ the

______describes the period from 1918 － 1930; the years after the end of World War I and en

The committee______ separated from their families for long periods of time in case that th

The American dream is most______ during the periods of productivity and wealth generated b