英文高手請進..20 points wor !! 仲唔入黎?!

錯:1.The cheering teams were taking a rest before the race began
岩:1.The cheering teams were taking a rest before the race begin.

錯:2.The school principal was staying in hospital during Sports Day.
岩:2.The principal was staying in hospital during Sports Day.

錯:3.All the runners were going back to the starting point after hearing the starting gun.
岩:All the runners were going back to the ending point after hearing the starting gun.

I didn't find anything wrong until I looked at the third one.
It would make much more sense if it was "All the runners went back to the starting point after hearing the starting gun." (though the sentence itself doesn't make too much sense anyway) I think your sentences aren't wrong but you probably used an inappropriate tense. It all depends on the context of the rest of your essay. I am going to go ahead and provide you with the possibly correct sentences - "The cheering teams took a rest before the race began", "The school principal stayed in (the) hospital on Sports Day" and "All the runners went back to the starting point after hearing the starting gun". I hope this helps.

1.The team that had encouraged it before the race started was taking a rest.
2.The head of the school was in the hospital during Sports Day.
3.After having heard the gun of the start, all runners planned to return to the
starting point.

1.The cheering teams were taking a rest before the race began.(begin)
2.The school principal was staying in hospital during Sports Day(is staying)