La tuerca seguía floja, así que mi hermana cogió el alicate y revisó otra vez el somier.

Because seguía is the imperfect, which describes an ongoing state or situation in the past.

Here, La tuerca seguía floja means the nut was still loose. The idea is that its looseness continued over time.

If you said siguió floja, it would sound more like it remained loose as a completed event or change in the story. In this sentence, seguía fits better because it sets the background situation before the next actions happened.

Because floja agrees with la tuerca, which is a feminine singular noun.

In Spanish, adjectives usually match the noun in gender and number:

• el tornillo flojo
• la tuerca floja
• los tornillos flojos
• las tuercas flojas

So floja is feminine singular to match tuerca.

Seguir can mean to continue or to still be in the same state.

So:

• seguía floja = was still loose
• seguía abierta = was still open
• seguía cansado = was still tired

This is a very common structure in Spanish for saying that a condition had not changed.

Así que means so, therefore, or so then.

It introduces the consequence of what came before:

• La tuerca seguía floja, así que...
• The nut was still loose, so...

It is very common in spoken and written Spanish.

A few similar expressions are:

• por eso = for that reason / that’s why
• entonces = then / so
• de modo que = so / therefore (a bit more formal)

In this sentence, así que sounds natural and straightforward.

Yes. In Spain, coger is a very normal verb meaning to take, to grab, or to pick up.

So mi hermana cogió el alicate means my sister picked up the pliers.

Important regional note: In much of Latin America, coger can have a vulgar sexual meaning, so people often prefer:

• agarró
• tomó
• recogió (depending on context)

But in Spain, coger is completely standard and neutral in everyday language.

Because Spanish often uses alicate as a singular noun, even though the tool has two arms and English uses the plural pliers.

So:

• el alicate = the pliers
• un alicate = a pair of pliers / a set of pliers

In some contexts, you may also hear los alicates, especially when referring to types of pliers or more than one tool. But coger el alicate is perfectly natural.

Because revisar means to check, to inspect, or to examine, while mirar just means to look at.

Here, the sister is not simply looking at the bed base; she is checking it again, probably to see whether the problem is fixed.

So:

• miró el somier = she looked at the bed base
• revisó el somier = she checked/inspected the bed base

Revisó is the more precise choice.

Otra vez means again.

So:

• revisó otra vez el somier = she checked the bed base again

Yes, de nuevo would also work:

• revisó de nuevo el somier

In many cases, otra vez and de nuevo mean the same thing. Otra vez is often a little more common in everyday speech.

Somier is the bed base, especially the frame or slatted base that supports the mattress.

It is a useful household word in Spain. Depending on context, English translations might include:

• bed base
• slatted bed base
• bed frame (sometimes, though not always exactly the same)

So in this sentence, the sister is checking the part of the bed structure, not the mattress itself.

Because somier is a masculine noun:

• el somier
• un somier

Its gender is something you simply have to learn with the word. There is no special rule here that would make it obvious to an English speaker, so it is best memorized together with the article: el somier.

Because they describe completed actions in the sequence of events.

The sentence sets up a background condition:

• La tuerca seguía floja = ongoing state in the past

Then it gives two actions that happened:

• mi hermana cogió el alicate
• y revisó otra vez el somier

Those are specific, finished actions, so the preterite is the natural choice.

This contrast is very common in Spanish storytelling:

• imperfect for background, conditions, ongoing situations
• preterite for main completed actions

It is the most natural neutral order in Spanish:

• subject: mi hermana
• verb: cogió
• object: el alicate
• then another verb phrase: y revisó otra vez el somier

Spanish word order is flexible, but this version sounds clear and normal.

You could change it for emphasis, but the given order is what a learner should probably use first.

Yes. The singular article el suggests a specific tool already known in the situation: the pliers.

If you said un alicate, it would sound more like a pair of pliers or some pliers, not one already identified.

So:

• cogió el alicate = she picked up the pliers
• cogió un alicate = she picked up a pair of pliers

The article helps show whether the object is specific or not.