Paso la mañana en la biblioteca y leo en silencio.

Spanish present tense can cover both:

• Habitual/routine: Paso la mañana… = I (usually) spend the morning…
• Current/ongoing (context-dependent): Paso la mañana… can also mean I’m spending the morning… if the situation makes it clear. If you want to force right now, Spanish often uses:
• Estoy pasando la mañana en la biblioteca… (less common than simple present, but possible)
• Or adds a time marker: Hoy paso la mañana… / Ahora estoy en la biblioteca…

Pasar has a very common meaning: to spend (time).

• Pasar + time period = to spend + time period: pasar la mañana / la tarde / el día / el fin de semana So Paso la mañana… is the standard way to say you spend the morning somewhere/doing something.

Both exist, but they don’t mean exactly the same thing in tone/usage:

• Paso la mañana… = neutral, very common.
• Me paso la mañana… = also common in many places, often more emphatic/colloquial, like I end up spending the whole morning… or I spend the morning (there) with a slightly stronger “that’s what I did.” In Latin America, Paso la mañana… is perfectly natural and widely used.

They express different ideas:

• Paso la mañana… = I spend the morning (that morning / the morning period). Spanish often uses the with parts of the day as a time block.
• Paso una mañana… sounds like I spend one morning (one specific morning as a unit)—less typical here.
• Por la mañana means in the mornings / during the morning (time of day) and is more like a general time frame:
  Por la mañana leo en silencio. = In the mornings, I read quietly.

Because en marks location (where you are):

• en la biblioteca = in/at the library (location) a marks movement/destination:
• Voy a la biblioteca. = I go to the library. So this sentence describes where the morning is spent, not the act of going there.

Spanish verb endings already show the subject:

• paso = I spend
• leo = I read So yo is usually unnecessary. You add yo for emphasis or contrast:
• Yo paso la mañana en la biblioteca, pero él se queda en casa.

Yes—by default, Paso… y leo… means the same subject (I) does both actions. If the subject changes, Spanish usually makes it explicit:

• Paso la mañana en la biblioteca y él lee en silencio.

Both are correct, but they feel different:

• leo en silencio = very common, natural, and emphasizes no noise / in silence
• leo silenciosamente = correct but more formal/bookish; it emphasizes the manner (silently/quietly) In everyday Spanish, en silencio is often preferred.

Yes, that’s very natural:

• Paso la mañana en la biblioteca leyendo en silencio. This uses a gerund (leyendo) to show how you spend the morning—reading is integrated as the activity during that time. With y leo, it feels more like two coordinated actions: I spend the morning… and (also) I read… (still perfectly fine).

Grammatically it most directly modifies Paso la mañana en la biblioteca (where you spend the morning).
But in normal interpretation, it also strongly implies the reading happens there too. If you want to remove ambiguity, you can clarify:

• Paso la mañana en la biblioteca y allí leo en silencio.
• Paso la mañana en la biblioteca; leo en silencio. (still implies it, but separates the ideas)