问题补充：
Nobody but doctors, nurses or those by Dr. Hu to enter the patients room.
A. invited; are allowed
B. are invited; are allowed
C. are invited; is allowed
D. invited; is allowed
答案：
A. invited; are allowed
B. are invited; are allowed
C. are invited; is allowed
(答案→)D. invited; is allowed
解析：考查过去分词做定语和主谓一致：句意：除了医生，护士或胡博士邀请的人没有人可以进入病人的房间。第一空填定语，因为those和invite是被动关系，用过去分词做定语，第二空是谓语，因为主语是but连接的，和前面的主语nobody一致，用单数is，选D。
