Questions & Answers about Quiero cuidar el planeta cada día.
In Spanish you normally use verb + infinitive directly, without a preposition like a:
So you never say quiero a cuidar. The a is not needed here.
In Spanish, singular countable nouns almost always need an article (el, la, un, una) unless there is a special reason not to use one.
When you talk about something in general, Spanish often uses the definite article:
- El perro es un buen amigo. = Dogs are good friends.
- El planeta here means the planet (in general).
You can’t say Quiero cuidar planeta; it sounds incomplete. It has to be Quiero cuidar el planeta.