Could you please check these sentences? Thank you very much.

1) Before he went to Celtic Camp, Johnny did some mock exams as a preparation (to prepare) for his A-level exams.
2) Kane suggests he should copy his essays from the net. Johnny refuses (to follow her advice) though he finds studying difficult.
3) Jack's DVD player doesn't work. Dave gives him some tipps but it doesn't work howsoever (all the same. Jack invites Dave to his house.
4) Dave accepts and says he will go the next day if he is not too busy.

2) the useage of "though" seems out of place here.

3) tips is the spelling, and I would not use "howsoever"

4) comma after day,

Sra

Certainly! Here are the checked sentences with suggested corrections:

1) Before he went to Celtic Camp, Johnny did some mock exams in preparation for his A-level exams.

Explanation: The phrase "in preparation for" is more commonly used to indicate the purpose or intention of doing something.

2) Kane suggests he should copy his essays from the internet. Johnny refuses to follow her advice, even though he finds studying difficult.

Explanation: It is more common to use "copy his essays from the internet" rather than "copy his essays from the net." Additionally, "even though" is a better phrase to use than "though" to indicate contrast.

3) Jack's DVD player doesn't work. Dave gives him some tips, but none of them work. Jack invites Dave to his house.

Explanation: Use "tips" instead of "tipps" and "none of them work" instead of "it doesn't work howsoever" to express that none of the tips provided by Dave were effective.

4) Dave accepts and says he will go the next day if he is not too busy.

Explanation: No correction needed. The sentence is grammatically correct as it is.