Thanks for your reply. But the 1st one shouldn't it be "I saw trapeze artists swinging in the air? And what about this "Don't let the students too noisy"? Is it better to say "Don't let the students be too noisy"?
1) I saw the trapeze artists swing in the air. OK, but I'd use 'through' rather than 'in'. 2) I lit up the hoop with fire. No. I set fire to the hoop or, possibly, I lit the hoop. 3) I am really afraid of heights. Fine.