They replaced the permanent staff with part-timers.

【replace，replaceable】他们用兼职人员来代替固定职员。

These articles, following those on Pocahontas and Lyell, enrolled him on the permanent staff of the North American Review.

这些文章，继 Pocahontas 和 Lyell 的文章之后， 使他成为了《北美评论》的固定员工。