witnessing

Her witnessing of the accident helped the police understand what happened.

用法提示：此处 witnessing 是名词，表示“见证（的行为）”，在句中作主语，前面用所有格 her 修饰。

They discussed the witnessing of the agreement during the meeting.

用法提示：此处 witnessing 是名词，指“见证（的行为）”，在句中作动词 discussed 的宾语。

The witnessing of the signing took only a few minutes.

用法提示：此处 witnessing 是名词，表示“见证（的行为）”，在句中作主语，由定冠词 the 和 of 短语修饰。