A model or an experiment in a science class can help students see things which would ______ remain hidden.
Someone took away my umbrella, I’d never expect it _______.
As is natural, a man as old as he _____ be very forgetful.
Only by shouting at the top of his voice ____________.
There was never any time for her to feel happy, _____ lots of people loved her.
Is this company _____ you visited Mr. Wang last week?