问题补充：
The hottest continent, Africa has a lot of resources, are still undeveloped.
A. many of them
B. many of whom
C. many of it
D. many of which
答案：
A. many of them
B. many of whom
C. many of it
(答案→)D. many of which
解析：本题中两个完整的句子之间没有连词连接，说明不是并列句，而是一个主从复合句。实际上是一个定语从句，先行词是a lot of resources，后面定语从句中的关系代词which指代先行词作为介词of的宾语。句义：最热的大洲，非洲有大量的资源，其中很多仍然没有被开发。A项应该在前面加上but，whom指代的先行词是人，it指代的是单数名词。故只有D项是正确的。
