.The public have been reminded to be _______of how the disease spreads.
Not until they left school________how much their teachers loved them and helped them.
It’s nice to see you again. What_________ since we last met?
--- Shall we take the 10:20 train? --- No. If we took that train, we ________too late.
--- I had thought he would be nervous in this speech competition, but he turned out to be calm. --- He________quite enough preparation for it.
Don’t give up regardless of difficulty and failure, ________ you’ll never achieve your goals.