The conference _____ a full week by the time it ends.

The conference _____ a full week by the time it ends.
A、would have lasted
B、had lasted
C、will have lasted
D、has lasted
【正确答案】：C
【题目解析】：will have done为将来完成时，强调在将来的某一时间，某件事情已经被完成了。