1) Luckily Jim didn't need to re-take the exam.

2) Despite being intelligent, he doesn’t do well at school. 

3) We stayed at home instead of going to the theatre.

4) We must replace the loudspeakers since the current ones aren’t satisfactory.

1, luckily it wasn't necessary for jim to take the exam again(need)

 => 1, Luckily Jim didn't need to re-take the exam.

2,although he is intelligent,he doesn't do well at school(despite)

=> 2, Despite being intelligent, he doesn’t do well at school. 

3,we didn't go to the theatre . we stayed at home(instead of)

=> 3, We stayed at home instead of going to the theatre.

4,we must replace the loudspeakers . the current ones aren't satisfactory(since)

 => 4, We must replace the loudspeakers since the current ones aren’t satisfactory.