Questions & Answers about El mantenimiento cuesta mucho.
Because mantenimiento is a masculine noun in Spanish, so it takes el.
A useful clue is the ending: many nouns ending in -miento are masculine, for example:
- el movimiento
- el nacimiento
- el conocimiento
So el mantenimiento is the normal form.
Cuesta is the third person singular of the verb costar in the present tense.
Here is the relevant part of the conjugation:
Since el mantenimiento is singular, the verb is singular too:
- El mantenimiento cuesta mucho.
If the subject were plural, you would use cuestan:
- Los mantenimientos cuestan mucho.
- Las reparaciones cuestan mucho.