My granny does crossword puzzles each day ______ her mind sharp.
These natural parks are very important for preserving many animals, which would ______ run the risk of becoming extinct(灭绝的).
The girl didn’t know who ______ for the broken vase.
______ with the size of the whole earth, the highest mountain does not seem high at all.
-- How long do you think it will be ______ the bus arrives here?-- No more than five minutes.
Making a proper choice ______ the future will probably make much difference in our life.