from/since

Neither is correct.
Since Monday, I have worked in another school. (Since refers to a point of time in the past, so the verb must be past.)
From is the start of a time period. The end of the period has to be in the phrase. The verb has to agree with the time period.

From next Monday on, I will work in another school. ( "on" means indefinite extent of time, future tense)

AlpheccaStars Neither is correct.

Since Monday, I have worked in another school. (Since refers to a point of time in the past, so the verb must be past.)

Hi

Why did you use the present perfect tense? Is it because you still work there?

Can I also say: I've broken my leg on Monday.

Yes. "Since" implies that the time period is not completed. "Have worked" means that I am still working at the other school.
In your second sentence, the simple past is better, since the action of breaking is completed and at a particular time.
I broke my leg on Monday.
The present perfect is used in cases such as this one:
I like to ski, but I am reckless and always go too fa

AlpheccaStarsIn your second sentence, the simple past is better, since the action of breaking is completed and at a particular time.

I broke my leg on Monday.

Yes, but it's still broken.

Thanks

Yes, it is still broken, but it is not still breaking. The breaking action is completed (unless there is something very strange going on

OK, it's a bit clearer now. Thanks.

Newguest I've broken my leg on Monday.

No! You can't use the present perfect in the same sentence with an action explicitly placed at a definite time -- on Monday in this case.
(But you can mention a definite time that the action began in a since clause.
I have been living here since 1985. )

CJ

NewguestFrom Monday I work in another school.
Since Monday I work in another school.

Can I use "from" and "since" in the same way in this case?

You don't want from.
If the Monday is in the past, then you want

I have been working at another school since Monday.
If the Monday is in the future, then y

AlpheccaStars Since Monday, I have worked in another school. (Since refers to a point of time in the past, so the verb must be past.)

Hi

But in this case we also use a definite period of time, i.e., Monday

Monday is not a period of time. It is a point in time.
You use a since clause with a point in time to tell when an action began. You combine it with the present perfect to indicate that it has continued up to the present moment, regardless when it began. The presence of the word since makes a big difference.
*I have slept at two o'clock is wrong.
I hav