Formal:
* 你在做什么？ (nǐ zài zuò shénme?) - This is the most common and literal translation, suitable for formal settings.
Informal:
* 你在干吗？ (nǐ zài gàn ma?) - This is a more casual and everyday expression, used among friends and family.
* 你在忙什么？ (nǐ zài máng shénme?) - This literally translates to "what are you busy with?", implying that you are doing something specific.
* 你做什么呢？ (nǐ zuò shénme ne?) - This is a softer and more inquisitive way of asking, often used with friends or close acquaintances.
In addition to the above, here are some other variations you might encounter:
* 你正在做什么？ (nǐ zhèngzài zuò shénme?) - This emphasizes that you are doing something right now.
* 你最近在做什么？ (nǐ zuìjìn zài zuò shénme?) - This asks what you have been doing recently.
The best choice for you will depend on the situation and your relationship with the person you are speaking to.