"I'll" vs. "I've"

[Burak]

English Language Tests, Intermediate level

ESL/EFL Test #119 "English Tenses", question 10

Sarah: Thank you very much. I shall be as quiet as a mouse but ......... just put the TV on.

(a) I'd
(b) I'll
(c) I've
(d) I'm

English Language Tests, Intermediate level

ESL/EFL Test #119 "English Tenses", answer 10

Sarah: Thank you very much. I shall be as quiet as a mouse but I'll just put the TV on.

Correct answer: (b) I'll

Your answer was: incorrect
Sarah: Thank you very much. I shall be as quiet as a mouse but I've just put the TV on.
_________________________

Why should I choose item b?

Burak

[Alan]

Hi Burak,

In this sentence the speaker says what he is going to do and that's why he says: I'll just put ... indicating I will/shall just....

The other form form I've (I have) would not work here because that would mean that he has already put the tv on.

Alan
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English as a Second Language
You can read my ESL story Womens' Day

[joker]

I need just an explanation:

the word 'just' in:

"Sarah: Thank you very much. I shall be as quiet as a mouse but I'll just put the TV on."

doesn't mean that he has 'already' put the TV on?
or it means that he is 'only' going to put the TV on?

thanks

[Alan]

Hi Joker,

The point is that the speaker promises to be quiet BUT says that he will just put the tv on/ in other words that's all he's going to do.

Alan
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English as a Foreign Language
You can read my EFL story A day in the life of a parliamentary candidate

[joker]

so 'just' means 'only'...

thanks a lot, just wanted to be sure...