A limpiar - a cenar

A limpiar - a cenar
 

From Antosh-and-Lin.com Sentence of the Day

Si me ayudas a limpiar, te invito a cenar.
If you help me clean up I will invite you out for dinner.

¿Alguien puede decirme por qué no hay una "a" antes de limpiar y cenar?

Gracias, Bob Ritter, Pensacola, Florida, USA

Creo que quieres saber por qué hay una 'a' antes de 'limpiar' y 'cenar'.
Es porque 'ayudar' e 'invitar' siempre van seguidos por 'a'.

ayudar a + infinitivo
invitar a + infinitivo

Remember, a Spanish infinitive does NOT have a built-in 'to'.
We English speakers are taught that 'ayudar' means 'to help'. That's not true. It means the same thing as our bare infinitive 'help'.
Spanish infinitives are all bare infinitives (there's no built-in preposition).
Some infinitives require that a preposition follow them when they're followed by an infinitive, and the preposition isn't always 'a'.

ayudar a (help to do something)
comenzar a (begin/start to)
invitar a (invite to)
ir a (go to)

soñar con (dream about)
contar con (rely on)

acordarse de (remember to)
cuidar de (be careful to)
dejar de (stop; fail to)
olvidarse de (forget to)
tratar de (try to)

consentir en (agree to)
dudar en (hesitate to)
pensar en (think about)
tardar en (take a long time to)

comenzar por (begin with)
esforzarse por (struggle to)
estar por (be in favor of)
optar por (opt for)

Some don't require a preposition where English does.

buscar (search for)
decidir (decide to)
confesar (confess to)
esperar (hope to)
intentar (try to)
preferir (prefer to)
soler (be accustomed to)
temer (be afraid to)

Rusty - Thank you very much. I have always felt uncomfortable with the "a" and as you said was taught that the Spanish infinitive had the "built in" to. It all makes more sense now. This has been a major help.

Glad to have been of some help.