occasion when造句不少于三个

Describe an occasion when someone gave you important help in a difficult situation.
Describe an occasion when you had to give a presentation to an audience.
In a sports team each pleyer has a clear role,and there are few occasions when members areconfused or uncertain of their roles.
people may meet with an occasion when you explain to sb but yet are not understand
It was a rare occasion when I was able to put xiaohua right.