"inthepast" 似乎是一个拼写错误或拼写不正确的单词。如果你指的是 "in the past"，那么它的用法是 句首句末都可以。例如：

1. In the past, many people lived in old houses.

2. Many people lived in old houses in the past.

在这两个例子中，"in the past" 都放在了句首，但也可以放在句尾，例如：

1. Many people lived in old houses. In the past.

2. In the past, many people lived in old houses.

因此，"in the past" 作为时间状语，在句子中的位置是灵活的，可以根据句子的需要放在句首或句尾。