我的English文法對嗎?

I will highlight your mistakes and give you the correct answer. If you need any explain, call me.

A. Joey Chan's Piano Concert
Joey Chan, one of the most famous pianists, is going to come to Hong Kong (at)
the twelth of December. She is going to stay in Hong Kong (for) two months.During her stay, Joey will perfrom at two piano concers ***(on) Christmas***. The first piano
cencert will start (at) seven o'clock (in) the evening at Hong Kong Cultural Centre (on) Christmas Eve.
Joey was born in Guangdong, the People's Republic of China, (since) 1980.She
won the first prize at the 12th Chopin International Piano Competition (in) October 1998.(For) then, she has been performing around the world.
Tickets for the concert are available for sale on the Internet starting fron 15th
December. The tickets will be malled to you (on) the day before the concert day .
Don't miss the chance .Enjoy the concert (in) winter!
________________________________________________________________
*** When we are talking about festivals and holidays, we will use prepositions "at" to express.
So, It should be (at) Christmas.
Almost correct for the others.

B.
1. I haven't seen you (on) last month.
2.I'm only free(on) saturdays.
3.I have a lesson (on) saturdays.
4.I'm free (in) the afternoon.
5.Shall we meet (at) 4:30 pm at the cinema?
6.I have to be back to my home (at) nine o'clock.
7. The film only lasts (by) two hours.

1. Because it is expressing the present perfect tense. So, when we say for a period of time, "for" and "since are the best.
In this situation, "since" is better.
And for last month, no preposition is needed.

2. correct

3. correct

4. correct

5. correct

6. correct

7. correct

Hope I can help you.

The explaination:-
A:-HK (on)--12th Dec
-----2 concerts (at)Christmas -----(not on)
-----(in) 1980,
-----(in) Oct 1998
-----(Since) then---(not for) = use present perfect or past perfect tenses=She's been Pianoing (since) 1998.

B:-1,(Since) last month------present perfect tense
---- 2,on,,3,on,4,in,5,at,6,at,
-----7,(for) 2 hours, (not by)

A.
~ Hong Kong (on) the twelveth of December
~ two piano concerts (at) Christmas
~ (in) 1980
~ (Since) then,

B.
1. since last month
7. for two hours

Not all correct.

Joey Chan, one of the most famous pianists, is going to come to Hong Kong (on) the twelth of December.

During her stay, Joey will perfrom at two piano concers (in) Christmas.

(Since) then, she has been performing around the world.

Enjoy the concert (of) winter!

B.1. I haven't seen you (since) last month.

These are all your mistakes.