It is well known to all that water, ___________ enough, can change into ice quickly.

       A. if cooling     B. though to be cooled     

C. when cooled        D. when is cooled

It is well known to all that water, ______ enough, can change into ice quickly．

It is well known to all that water, ______ enough, can change into ice quickly．

1. A.
   if cooling
2. B.
   though to be cooled
3. C.
   when cooled
4. D.
   when is cooled

It is well known to all that water, ______ enough, can change into ice quickly．

       A．if cooling            B．though to be cooled

       C．when cooled            D．when is cooled

It is well known to all that water, ______ enough, can change into ice quickly．