do vs did

Hello everyone,

I just want some confirmation on the following sentences:

1) How do you do ?
2) How did you do ?
3) How do you do it ?
4) How did you do it ?

Here is my interpretation of what they actually mean:-

#1 is the standard greeting between two people who've just met.

The speaker in #2 could be enquiring about the performance of a friend in an exam, a race (sports) or an interview, among others.

In #3, the speaker is astonished at someone's ability to multitask and accomplished so much in a single day.

#4, the recipient of the "query" in #3 is reminiscing about the good ol days when he/she was multitasking and leading a very busy life.

Anything wrong with the sentence, grammatically ? Are my interpretations spot on ?

Your interprtations are fine, though 3 would require some intonation to convey that specific mewaning in spoken English. ;-)

I would say that "How did you do it?" is more likely to be asked of someone else rather than oneself.

:)