[译] 如果发生创伤,最重要的是预防感染。
[误] If an injury should happen, it is the very important to prevent infection.

[正] If an injury should occur, it is the very important to prevent infection.
[注] injury(伤)/pain(痛)/disease(病)的“发生”常用 occur/develop/result, 但不用 happen。happen 多指发生事故, 如: How did the accident happen?事故是怎样发生的? /If anything happens to him, let me know. 如果他出了什么事,务必告诉我。