.The Internet __________ of great value to us during our project.A was proved B proved C was proving D was being proved
Are there any possible signs in nature that can ________ earthquakes with accuracy?
The principle of the heating system in this building is that pipes ________ hot water from the boiler to every part of it.
People’s working efficiency usually decreases more or less when the temperature _________ 35℃ or even higher.
It is widely accepted reported in the western media that the drug ______ is now becoming a leading cause of teenager crimes.
“Boys and girls, you are asked to submit a(n) _______ of about 100 words of the lecture given by Professor Yu tomorrow” , said the teacher.