Audiences were greatly ______ by the video class about weightless conditions _____ in Tianggon-1 space station.
The government has taken some measures to reconstruct the earthquake-hit areas, but it must be some time ________ everything returns to normal.
________ twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.
A good speaker is supposed to manage to ________ the listeners what he means.
We agreed to accept ________ they thought was the best professor in the college.
I don’t know who invented ________ telephone. It’s really ________ most useful invention.