各种英语高手们！帮我看看这道题吧We stood there for _ seemed hours,

各种英语高手们！帮我看看这道题吧We stood there for _ seemed hours,then we heard someone co ming towards the front door.A that B what为什么是B 望给出详细解答

what seemed (to be) hours 作宾语 =We stood there for a long time.
由于无先行词，不用that

我们似乎在那儿站了几个小时，然后听见有人朝前门过来了。