the deletion of a great deal of irrelevant material删除大量不相关的资料

Permanent data deletion usually requires several steps.永久性地删除数据通常需要几个步骤。

David wanted to make several deletions and additions to the text.戴维曾想对文本做几处增删。

I restored the deletion and added a citation.我还原了被删掉的内容, 并补充了引文。