There are b___ a new bridge over the river
问题描述：
There are b___ a new bridge over the river
答
They are building a new bridge over the river.
答
They are building___ a new bridge over the river
答
句子是不是有打错的地方呀,我猜正确句子应是：They are b____ a new bridge over the river.
答案为：building
题意：他们正在河上修建一座新桥.