Usages of útil
Estoy seguro de que el libro verde es útil.
I am sure that the green book is useful.
Este consejo es muy útil.
This advice is very useful.
Si vas a entregar un trabajo importante, desconectar el teléfono es tan útil como tomar un breve descanso.
If you are going to hand in an important assignment, disconnecting your phone is as useful as taking a short break.
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