I made the changes you wrote. Can you please check if everything is OK?
1) The rooms are all set in a way that one cannot see from one room to another; besides, each room has a Gothic window and ornaments of the same colour.
2) Only the last one is all black with a red window. All the guests are enjoying themselves and dancing. However, when a clock with a pendulum strikes the hours, the orchestra stops playing and the people stop dancing, as if they were all frozen.
3) They all resume their activities as soon as the clock finishes chiming. When the clock strikes midnight, a man with a red costume turns up.
4) He is covered in blood and wears a mask on his face that makes him similar to a dead man. The man moves to and fro with solemn movements.
5) When Prince Prospero tries to stop him, he immediately dies. The same happens to his friends who try to touch him but realize there is no tangible form under the costume.
6) One by one, all the people in the castle die, and darkness falls all over the place.
He likes teaching adults.
He likes taching German to adults.
He likes teaching adults German.
Which are possible?
2 answers
4. ... wears a mask that makes him look like a dead man.
5. ... happens to Prospero's friends who try to touch the dead man, but realize...
All three of the last sentences are fine. They have slightly different phrasing, but they are all grammatically correct.