夕方の雷にびっくり I was surprised by the thunder at night

夕方ちょっと用があって事務所に行ったら

ものすごい雷鳴と雨。

びっくりです。

まさにお天気急変。

大気不安定。

この件、英語で

I was surprised at the thunder 

or 

I was surprised by the thunder

どっちかなあとChatGPTに聞いてみたら、

Both "at" and "by" can be used to express surprise about something. However, in this context, "by" is more commonly used. So, the correct phrase would be: "I was surprised by the thunder."

とのことでした。

外国語はこの辺が難しい。