Cuando llegué a casa, el contestador seguía lleno y la cobertura del móvil era muy mala.

Because llegué refers to a single completed event in the past: the moment the speaker arrived home.

Spanish often uses:

• the preterite for completed actions that move the story forward
• the imperfect for background description

So Cuando llegué a casa means When I got home / arrived home, marking the time at which the other past situations are being described.

Because they describe ongoing background situations at the moment of arrival.

• el contestador seguía lleno = the answering machine / voicemail was still full
• la cobertura del móvil era muy mala = the mobile signal was very bad

These are not seen as single completed events. They are states or conditions that were already true when the speaker arrived.

This is a very common Spanish pattern:

• preterite for the main event: llegué
• imperfect for the circumstances around it: seguía, era

That would change the meaning quite a lot.

• Cuando llegué a casa = When I arrived home
  A specific completed moment.

• Cuando llegaba a casa = usually When I was arriving home or Whenever I used to arrive home
  This is more open-ended, less punctual, and depends more on context.

In this sentence, llegué is the natural choice because the speaker is talking about one particular arrival.

In Spanish, casa often behaves like home in English when used with verbs of movement.

So you say:

• ir a casa = to go home
• llegar a casa = to get home
• volver a casa = to return home

You use a la casa when you mean a specific house as a physical building, not simply home.

For example:

• Llegué a casa = I got home
• Llegué a la casa de Ana = I arrived at Ana’s house

In Spain, contestador usually means an answering machine or, by extension, voicemail.

Depending on context:

• contestador automático = answering machine
• buzón de voz = voicemail

In everyday use, contestador is very natural, especially in contexts involving recorded messages. In this sentence, seguía lleno suggests that no more messages could be left.

Because seguir + adjective means to continue to be or to still be.

So:

• estaba lleno = it was full
• seguía lleno = it was still full

Using seguía adds the idea that it had already been full before, and it had not changed by the time the speaker got home.

That nuance is important here: the situation was ongoing and remained the same.

Here it means the phone’s signal, reception, or network coverage.

In natural English, you would often translate it as:

• the mobile signal was very bad
• reception on my phone was very poor

In Spain, móvil is the normal word for mobile phone. A Latin American learner might be more used to celular or teléfono celular, but in Spain móvil is the standard everyday term.

Because de + el contracts to del in Spanish.

So:

• de el móvil → del móvil

This contraction is mandatory, except with proper names or titles like El Greco:

• el cuadro de El Greco — not del Greco

But in normal cases like this one, del is required.

Because mala is an adjective agreeing with cobertura, which is a feminine singular noun.

• la cobertura → feminine singular
• therefore: mala

Compare:

• el servicio era malo
• la señal era mala

Mal is different:

• usually an adverb: habla mal
• or the shortened form of malo before a masculine singular noun: un mal día

So here, mala is the only correct form.

Because ser is more natural here for describing the quality of the signal/reception.

• era muy mala = the signal was very bad

With cobertura, Spanish commonly says:

• la cobertura era mala
• había poca cobertura
• no tenía cobertura

Using estar mala with cobertura sounds odd to many speakers. Also, estar malo/a often suggests meanings like ill, spoiled, or in bad condition, which do not fit well here.

So era muy mala is the idiomatic choice.

Because Spanish often leaves out subject pronouns when the verb ending already makes the subject clear.

• llegué already means I arrived
• so yo llegué is usually unnecessary

Spanish is a pro-drop language, so pronouns like yo, tú, él, etc. are often omitted unless the speaker wants emphasis, contrast, or clarity.

For example:

• Cuando llegué a casa... = normal
• Cuando yo llegué a casa... = more emphatic, like When I got home...

The accent mark shows that the stress falls on the last syllable: lle-gué.

This matters because:

• llegue would be stressed differently
• llegué is the correct preterite first-person singular form of llegar

So the accent is not optional. It helps mark both pronunciation and grammatical form:

• llego = I arrive / I am arriving
• llegué = I arrived

Yes. Lleno is an adjective describing el contestador, which is masculine singular.

So:

• el contestador → lleno
• la bandeja → llena
• los buzones → llenos

Agreement in Spanish is very important: adjectives usually match the noun in gender and number. Here, lleno is masculine singular because contestador is masculine singular.