It started at 7:00 p.m and ___on for another half an hour.A.has B.was C.had been D.will be

It started at 7:00 p.m and ___on for another half an hour.A.has B.was C.had been D.will be
It started at 7:00 p.m and ___on for another half an hour.A.has B.was C.had been D.will be

It started at 7:00 p.m and ___on for another half an hour.A.has B.was C.had been D.will be
It started at 7:00 p.m and (will be) on for another half an hour.
答案是 D.will be
怎么知道呢?
整个句子是
It started at 7:00 p.m and (will be) 【going】on for another half an hour.
【going】是隐含的.

句子是完整的句子吗？

D. will be