The science of medicine,-----progress has been very rapid la

The science of medicine,_____progress has been very rapid lately,is perhaps the most important of all the sciences
A,to which B,in which
C,which D,with which
I,who_____youre friend,will try my best to help you
A,be B,am C,are D,is
Even at the moment he didn't come to our help,_____made us very disappointed
A,who B.that C,which D,what
Is there anyone in your class_____family is in the city?
A,whose B,which C,who's D,who
要写为什么具体一点