—Is Pro.Smith giving the speech today?—It__________ be him. He is abroad right now.
The flu is believed __________ by viruses that like to reproduce in the cells inside the human nose and throat.
There were violent winds of 120 kilometers per hour or more in a hurricane,__________ huge waves, heavy rain and floods.
If city noises __________ from increasing, people __________ shout to be heard even at the dinner table in 20 years from now.
We have kept in __________ touch with each other for two years and he always gives me good advice on __________ phone.
We can't __________ to wait any longer or we'll miss the plane.