Past Progressive tense with the when phrase?

[Yura Reiri]

When we use the past progressive tense as in,

I was actually planning to send you a message.

Do we still have to continue it with the when phrase?

I was actually planning to send you a message when I heard you knocked.

Thank you!

 

[Mar Rojo]

Not necessarily.

 

[Rover_KE]

Your sentence should be

'I was actually planning to send you a message when I heard you knocking.'

You could also say

'I was actually planning to send you a message when you knocked at the door.'

Rover

 

[Yura Reiri]

Your sentence should be

'I was actually planning to send you a message when I heard you knocking.'

You could also say

'I was actually planning to send you a message when you knocked at the door.'

Rover

Thank you for that, Sir.

May I just know what rule is that? I never get used to it. But now, I will.

Examples:

incorrect:
heard you knocked
help you accomplished

correct:
as what you said, heard you knocking
help you accomplish