I am trying to understand the dialogue being spoken by the narrative character on the page below, specifically the fourth line of dialogue from the right in the picture.
「……さっきは何で、あんなことを？」
What is the implied-verb represented by the sentence-ending を in the above sentence, or is there a trick to figuring out what that verb might be, as mentioned here and here？
何で、あんなことを?
Why did you ... such a ...?
If you understand the story correctly, the implied verb should be self-evident. What happened to him a moment before (さっき)? What is her response to this question?
The omitted verb is する/やる ("to do").
何で、あんなことをした(んだ)?
Why did you do such a thing?
Judging from what's written in this page, あんなこと ("such a thing") refers to her (mock) attempt to kill the speaker with a knife.
