Please, help me to understand the subtle differences between these sentences. As in cases 4) and 5)
Can I use the 做 straight without other words before it? Thank you very much!
你在做什么? = What are you doing? --> 在 indicates it is in the progressive tense, you can add an indicator to make it a past progressive, for example, 你昨天在做什么? but it doesn't work with the future tense
你明天在做什么？ (ungrammatical) 在 is used to indicate a progressive tense, you can't use it with the future tense
你明天要做什么？ = What do you need/ want to do tomorrow
你明天做什么？ = What (will) you do tomorrow --> will is implied by the word 'tomorrow'
你做什么? = what are you doing? --> 在 (present progressive tense) is implied in the context when there's no indication of past or future tense, we presume it is in the present and is ongoing
