( ) 16. ----- Has John arrived yet? ----- No, she _______ an hour ago.
We must ______ known to all that smoking is harmful to heart.
China is larger than ______ around in population.
Susan,______ university student from Europe, teaches me ______ art in her spare time.
A poet and artist ______ coming to speak to us about Chinese literature and painting tomorrow afternoon.
Generally, there may be several different ______ to the same issue.