.The fresh water in Canada has one-third of the world’s total, much of ____ is in the Great Lakes.
—Sorry, I forgot to lock the door. —______ Mike can do it later.
—Do you know ____ made him successful in his career? —Yes. His hard work and determination, of course.
With many cities in China dreadfully blanketed by thick haze, the environment problem is _____ Chinese people concern most nowadays.
The doctor tried to laugh my brother ____ his fears about the coming operation.
—Did you manage to get in touch with David? —No, I didn’t. I ______ him up, but there was no answer.