一头牛一天吃草16千克，9头牛一周吃草____千克。
— ______ people travel every year?
— Perhaps when we are talking about it, more than 100 planes have taken off around the world.
— Were you at home _________?
— No, I was at school.
①给人民带来了沉重的灾难 ②大的诸侯国消灭小的诸侯国，实现了局部的统一
③是社会生产力提高的标志 ④促进了各民族的相互交融
学者认为，18世纪中后期的西方“选择了海洋”，而中国则“选择了陆地”。“选择了陆地”是指中国
