1.答案:C.
2.
1)楼主理解完全正确.
此题考查定语从句和单词progress的用法.
2)先行词是the science of medicine,关系代词which等同于先行词,在定语从句中充当介词in的宾语.
即正常句序的定语从句为:
in which progress has been very rapid
=in the science of medicine progress has been very rapid
=progress has been very rapid in the science of medicine
或=progress in the science of medicine has been very rapid
3) 楼主可能打错字了,此题中的progress是不可数名词,后面应该是形容词rapid做表语,而不是副词rapidly.