1. We didn't follow the tradition of decorating the house on Tet holiday -> The tradition of decorating the house on Tet holiday was not followed by us.
2. It's not a good idea for children to go out without adults when it gets dark -> Children shouldn't go out without adults when it gets dark.
3. It is a custom in my family is to have breakfast at home on Sundays -> We have the custom of having breakfast at home on Sundays in my family.
4. It's not a good idea to hit the bowl with your chopsticks because this may bring bad luck to the person.