推测过去的事情。。。
如果是过去的事实:
Over a hundred people 【have been driven away】 from their homes.
或 Over a hundred people 【were driven away】 from their homes.
如果只是推测过去:
不太确定:
Over a hundred people 【may/might haven been driven away】 from their homes.
更为确定:
Over a hundred people 【must haven been driven away】 from their homes.