Question

—Fire is very useful to human!
—Yes, especially in winter a fire _____________warm

1. A.
   used to keep
2. B.
   can be used to keep
3. C.
   is used to keeping
4. D.
   was used to keeping

Answer 1

B
考查固定用法。used to do，过去常常，现在已不再如此；be used to do sth.被用于做某事；be used to doing sth.习惯于做某事。根据句意，应是火被用来取暖。所以选B。