The train leaves at _________and arrives at _________.

A．10 a.m.;9 p.m.

B．a.m.10;p.m.9

C．ten a.m.o’clock;nine p.m.o’clock

D．10 a.m.in the morning;9 p.m.in the evening

简述承保实务中，保险人可以解除合同的几种情形。