去写作业用英语表达就是 do homework。这是一个非常常见且直接的表达，用于描述完成学校分配的家庭作业。

例如：

1. She's been beavering away at her homework for hours.

2. I need to do my homework before I can go out.

3. Do your homework carefully.

如果你需要更具体的表达，例如强调写作过程，可以使用 "Do writing assignments" 或 "Work on written tasks"。对于特定科目的作业，如数学、阅读或科学，可以相应地使用 "Do math homework"、"Do reading assignments" 或 "Do science projects" 等表达。