【2015·浙江】If steel is heavier than water, why are ships able to on the sea?
The pianos in the other shop will be ________, but ________.
John plays football ________, if not better than, David.
Which is ________ country, Canada or Australia? (NMET1992)
How beautifully she sings! I have never heard________.
If there were no examinations, we should have ________ at school.