The children promised to return soon.
Meaning: This means the children said they would come back to ride the carousel again soon.
Choice of Words: Children are young people. Promised means to make a formal statement or assurance that one will do something. Return means to come or go back to a place or condition. Soon means in a short time or without delay. When you put them together, "The children promised to return soon" conveys the children's eagerness to visit the carousel again in the near future.
Alternative Expressions
Related Expressions