A. electromagnetic energy
B. electromagnetic energy travels through space
C. came from the sun
D. when a change in the nucleus of an atom takes place
E. when the sunrays are fierce
F. chemical energy is generated The energy stored in coal ______.

A．It must be able to swim.
B．It must keep walking round the pool.
C．It can distinguish between a swimmer and a shadow.
D．It can save a life within a few months.