Перевидите на 1.когда катя путешествовала по америке, она узнала что знаменитая певица пороводит концерт в лос-анжелесе. 2. я смотрел телевизор, в то время когда случилось ужасное пришествие. 3.когда прозвенел звонок ученики писали сочинения. 4.мы возвращались домой в то время когда шёл снег.

1.When Katya traveled to America,she learned that the famous singer holds a concert in Los Angeles.
2. I was watching TV, at a time when the worst has happened coming.
3. When the bell rang the students wrote essays.
4.We came home while it was snowing.

When katya traveled to America, she learned that the famous singer is conducting a concert in Los Angeles
i was watching TV ,at the time when the terrible dreadful event
when the bell rang the students wrote the composition
we returned home at a time when it wassnowing