13. Our bad living habits will destroy the earth. Only by changing ________we live can we save the earth.
A. that B. what
C. how D. where
10. She was so angry at ______ he was doing ________ she stayed up all night.
A. that; that B. that; which
C. what; that D. what; as
After three days' waiting, there was a little doubt in the mother's mind _______ the police could find her lost child.
A. how B. that
C. where D. whether
Nowadays people become more practical and buy only _______ they need.
A. where B. which
C. when D. what
The reason ______he didn't come was ______he was ill.
A. why; that B. that; why
C. for that; that D. for which; what
_____manners are very important in every country is known to all，but the trouble is that different countries have different ideas about ______good manners are.
A. That；what B. That；that
C. What；that D. What；what
