After 15 long years of hard negotiations, China became a formal

After 15 long years of hard negotiations, China became a formal member of the World Trade Organization on Dec. 11，______.
A、2001
B、2002
C、2000
D、1999
【正确答案】：A
【题目解析】：After 15 long years of hard negotiations, China became a formal member of the World Trade Organization on Dec. 11，2001.
参见教材P283。