Pasamos palabra siempre que necesitemos comparar la respuesta.

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

• pasamos already tells you the subject is we
• adding nosotros is possible, but it would usually add emphasis or contrast

So:

• Pasamos palabra... = We pass...
• Nosotros pasamos palabra... = We pass... with extra emphasis, like we do

This is the part most learners would probably find least transparent.

In Spain, pasar palabra is an idiomatic expression. Depending on context, it can mean things like:

• to pass / skip a question or turn, especially in a game
• sometimes to hand over the floor to someone else

That is why it may not make perfect sense if you translate it word for word.

Also, pasamos palabra is more idiomatic than literal. If you said pasamos la palabra, that more clearly suggests we give the floor to someone else.

So the exact nuance depends a lot on the situation.

Because some Spanish expressions are fixed or semi-fixed and do not always use an article where English learners might expect one.

With this idiomatic use, pasar palabra works as a set phrase. It is not simply the ordinary noun word used literally.

Compare:

• pasar palabra = idiomatic expression
• pasar la palabra a alguien = to give someone the floor / let someone speak

So the missing article is tied to the expression itself.

Here siempre que means whenever or every time that.

So:

• siempre que necesitemos... = whenever we need...

Be careful, because siempre que can also mean as long as in other contexts. But in this sentence, the most natural reading is temporal: whenever.

Because after siempre que, Spanish often uses the subjunctive when the situation is not presented as a known fact, but as something that may happen in the future or whenever the occasion arises.

So:

• siempre que necesitemos = whenever we need to
• this has a sense of possible/repeated future situations

If you said:

• siempre que necesitamos

that would sound more like a habitual fact: whenever we do need to / every time we need to.

In other words:

• subjunctive = open, possible, future-oriented
• indicative = factual, habitual, known

It is the nosotros form of the present subjunctive of necesitar.

The present subjunctive forms are:

• yo necesite
• tú necesites
• él/ella/usted necesite
• nosotros/nosotras necesitemos
• vosotros/vosotras necesitéis
• ellos/ellas/ustedes necesiten

For regular -ar verbs, the present subjunctive endings are:

• -e, -es, -e, -emos, -éis, -en

Because after necesitar, when the same person does both actions, Spanish uses an infinitive.

Here the subject is we for both verbs:

• necesitemos = we need
• comparar = to compare

So:

• necesitemos comparar = we need to compare

You would only use another conjugated verb if the subject changed, for example:

• Necesitamos que ellos comparen la respuesta.
• We need them to compare the answer.

Because Spanish often uses the singular when referring to:

• one specific answer
• or the answer as a general concept in the activity

So la respuesta can mean:

• the answer to a particular question
• or the answer being discussed at that moment

If the context involved several answers, then las respuestas would also be possible.

Good question. In Spanish, comparar can work in a few ways:

• comparar X con Y = compare X with Y
• comparar X y Y = compare X and Y
• sometimes just comparar X if the second thing is understood from context

So comparar la respuesta is possible if what you are comparing it with is already obvious.

For example, the full idea might be something like:

• comparar la respuesta con la de otra persona
• compare the answer with someone else’s

But Spanish can leave that second part unstated if the context makes it clear.

It can be understood as a normal present tense, but in practice Spanish often uses the present for:

• routines
• procedures
• classroom instructions
• agreed group actions

So here pasamos may sound like:

• we pass whenever we need to compare the answer
• or even let’s pass whenever we need to compare the answer, depending on context

Spanish uses the present this way quite naturally, especially in instructions or descriptions of how an activity works.

The grammar is understandable, but pasamos palabra is quite context-dependent and may sound a bit unusual on its own unless the situation is very clear.

The most natural part grammatically is:

• siempre que necesitemos comparar la respuesta

That part is straightforward.

The part a learner should pay closest attention to is:

• pasamos palabra

because it is idiomatic and not something you can always decode word by word. So if it sounds slightly odd to you, that is a reasonable reaction.