It was ______ the old clock that the old man spent the whole morning at home.
The cake is delicious. May I have ________ one?
John seems puzzled about ________ the question meant.
All his free time is ______ by volunteer work, but he feels it meaningful.
The athletes competed ________ each other for gold medals in the Olympic Games.
--Can a plane fly ________ the Atlantic Ocean?--Yes, but it needs to go________ the clouds for hours.