Expressions with WITH/IN: He was writing (with or in) my pen

[Tom]

Hello everybody

Please guide me about the correct prepositions.

1- He was writing ----------my pen. (with-in)
2- Please do not write ---------- chalk.(with-in)

Thanks

Tom

[Mister Micawber]

.
1-- with (pen is modified)
2-- with or in (chalk is unmodified)
.
_________________
Native English teacher at Mister Micawber's

[Tom]

I am veryyyyyyyyyyyyy
sorryyyyyyyyyyyyyyyyy, Mr Micawber

I could not understand the answer

Could you please elaborate it for me a bit?

Thanks a lot

Ever yours

Tom

[Sakoos]

These are sentences I wrote

1. Please write in ink, if not your exam will not be graded.
2. I think the picture will be more pleasant when we colour with a brush rather than with a pencil.

They might not sound refined as they should be.

Petch

ESL intermediate Student

[Mister Micawber]

.
1-- with (pen is modified-- it has an adjective, 'my')
2-- with or in (chalk is unmodified-- it has no adjective or determiner)

PS: Please do not add extra letters to words-- it looks childish, Tom.
.
_________________
Native English teacher at Mister Micawber's