This kind of fridge was invented ___ Qingdao ___ 2006.
问题描述：
This kind of fridge was invented ___ Qingdao ___ 2006.
答
This kind of fridge was invented ___ Qingdao ___ 2006.
答案是：in
2006年青岛发明了这种冰箱两个空都是in吗This kind of fridge was invented( in )Qingdao ( in )2006