Preposition

[Sang]

Tom fue el ultimo "en" llegar.
No conozco de "a" ninguna de las dos chicas. (is this part of the personal a?)
Fui "de" viaje con el(him).

Hi, can you let me know where are these extra prepositions in the quotation marks of the above sentences come from? thank you!

[Rusty]

There are no extra prepositions in the first and last sentences. Each is necessary and must be said in order for the sentence to make sense.

en llegar = 'to arrive' (a Spanish infinitive never carries an implied 'to')
de viaje = 'on a trip' (after a verb); 'travel/traveling' (after a noun)

conocer a alguien = 'know someone' (the personal 'a' is required)
conocer de algo/alguien = 'know about something/someone' | 'know of something/someone' | 'be acquainted with something/someone'
(Here I'm guessing that someone threw in a personal 'a'. It doesn't seem necessary to me, but I'll defer to a native speaker for a better explanation, if any.)

[AngelicaDeAlquezar]

Unfortunately, one has to learn mostly by heart the prepositions that go with the verbs. It's a matter of practice until you get them almost instinctively.

"Personal a" is always necessary. It's, as Rusty said, a way to show respect for the person, giving them a different treatment than things or animals.

- Conozco a Juan desde hace dos años.
I have known Juan for two years.
- Conozco esa historia. La leí cuando era niña.
I know that story. I read it when I was a child.
- Conozco esos pájaros. Vienen todos los días.
I know those birds. They come every day.

- Me comí un postre delicioso. (Here, "me" is working as an intensifier, to stress the fact that I was the one eating the dessert.)
I ate a delicious dessert.
- El león se comió al dentista. ("Se" is working the same as in the previous example.)
The lion ate the dentist.

[Rusty]

The question I had was whether 'conocer de a ninguna' is proper. I found almost no evidence to support it. I have plenty of evidence that no personal 'a' is used when the verb is 'conocer de'. Thoughts?

[AngelicaDeAlquezar]

Oh, I see.
Well, I think "conocer de" is rather archaic, and mostly used in legal language, but I don't think "a" is ever used after "de" here.

- El juez Pérez es quien conoce del juicio contra mí.
Judge Perez is the one presiding the trial against me.
- Este tribunal conoce de materia civil.
This court deals with civil law.
- El abogado conoce de derecho.
The lawyer knows about law.
- Conocimos de su llegada al regresar del viaje.
We knew about his arrival when we came back from our trip.
- No conocí de la existencia de mi hermano hasta que mi padre murió.
I didn't know I had a brother until my father died.
- No conozco de ninguna persona que quiera enfermarse.
I don't know about anyone who would like to get sick.
- Mi abuelo conocía muy poco de Pedro López, su padre.
My grandfather knew very little about Pedro Lopez, his father.
- El rey no conocía del mago que había llegado al reino.
The king didn't know about the wizard who had arrived to the kingdom.
- Cuando nos casamos, yo conocía de Laura, su exesposa.
When we got married, I knew about Laura, his ex-wife.

[Sang]

Greatly appreciate both.