I really hope someone can check my sentences on Christmas holidays.

Thank you very very much in advance!

1) I had planned to do a lot of things during my Christmas holidays but unfortunately I didn't get around to doing them all.
( and NOT I had no time to do all of them)
2) I decided (?) to rest after the hard work at school.
3) On Boxing Day I left for "St Moritz", a ski resort in the Alps, where I celebrated New Year's Day with my friends
4) I stayed there till January 28.
5)All in all, I spent a good Christmas time or I enjoyed my Christmas holidays.
6) How are the possible prepositions with "Christmas holidays"
During/on/over my Christmas holidays I stayed at home (in my IS WRONG?)
7)On Christmas Eve I exchanged Christmas greetings with my relatives and we had dinner together.It is a tradition of (in?) my familiy because Christmas Eve is the day of my aunt's birthday.
8) On Christmas Day I stayed at home because I was ill and I went to bed right after midnight.
9) I finished my homowork on January 7 as I did not want to do any homework on the day before school began (or on January 8)
10) When the teacher saw the blown bulb, he got frightened and urged us to go(?) under our desks. A few minutes later he told us to go back to our places and he continued his lesson again. (Is this version better?)

Everything you've written is possible, but be careful of the spelling in #9. "homowork" is "homework"

For 10 = either is possible.

Sr

I'd be happy to check your sentences on Christmas holidays! Here are the corrections and explanations:

1) I had planned to do a lot of things during my Christmas holidays, but unfortunately, I didn't get around to doing all of them.
Explanation: This sentence is grammatically correct. However, you can replace "I didn't get around to doing them all" with "I didn't have time to do all of them" to convey the same meaning.

2) I decided to rest after the hard work at school.
Explanation: This sentence is grammatically correct. No changes are necessary.

3) On Boxing Day, I left for "St. Moritz," a ski resort in the Alps, where I celebrated New Year's Day with my friends.
Explanation: This sentence is grammatically correct. No changes are necessary.

4) I stayed there until January 28.
Explanation: This sentence is grammatically correct. However, you can use "till" instead of "until" if you prefer.

5) All in all, I had a good Christmas time, or I enjoyed my Christmas holidays.
Explanation: This sentence is grammatically correct. No changes are necessary. You can use either "had a good Christmas time" or "enjoyed my Christmas holidays" to convey the same meaning.

6) How are the possible prepositions with "Christmas holidays"? During/on/over my Christmas holidays, I stayed at home. (Is "in my" wrong?)
Explanation: The prepositions "during," "on," and "over" can all be used with "Christmas holidays." However, using "in my" in this context is not necessary and sounds a bit awkward. It is better to say "during/on/over my Christmas holidays" without adding "in my."

7) On Christmas Eve, I exchanged Christmas greetings with my relatives, and we had dinner together. It is a tradition in my family because Christmas Eve is the day of my aunt's birthday.
Explanation: This sentence is grammatically correct. No changes are necessary. The correct preposition to use here is "in my" to indicate the ownership of the tradition.

8) On Christmas Day, I stayed at home because I was ill, and I went to bed right after midnight.
Explanation: This sentence is grammatically correct. No changes are necessary.

9) I finished my homework on January 7 because I did not want to do any homework on the day before school began (or on January 8).
Explanation: This sentence is grammatically correct. However, you can replace "because" with "as," as it gives the same meaning in this context.

10) When the teacher saw the blown bulb, he got frightened and urged us to go under our desks. A few minutes later, he told us to go back to our places, and he continued his lesson. (Is this version better?)
Explanation: This sentence is grammatically correct. The revised version you provided is also correct and conveys the same meaning. Both versions are grammatically acceptable.