Comparamos el regloscopio con el frenómetro.

Comparamos is the 1st person plural form of comparar — we compare or we compared.

In this sentence, it comes from:

• comparar = to compare
• comparamos = we compare / we compared

Spanish often leaves out the subject pronoun, so comparamos by itself already tells you the subject is we.

Because Spanish usually omits subject pronouns when the verb ending already makes the subject clear.

So:

• Comparamos el regloscopio con el frenómetro.
• Nosotros comparamos el regloscopio con el frenómetro.

Both are correct, but the version without nosotros is more natural unless you want to emphasize we.

For example, you might include nosotros if you want contrast:

• Nosotros comparamos el regloscopio con el frenómetro, pero ellos no.

It can mean either one, depending on context.

For many -ar verbs, the 1st person plural present and the 1st person plural preterite look the same:

• present: we compare
• preterite: we compared

So comparamos is ambiguous by itself.

Usually, context makes it clear:

• Hoy comparamos el regloscopio con el frenómetro. = Today we compare / are comparing...
• Ayer comparamos el regloscopio con el frenómetro. = Yesterday we compared...

Because both regloscopio and frenómetro are being treated as specific masculine singular nouns.

So:

• el regloscopio = the regloscope
• el frenómetro = the brake tester / brake meter

In Spanish, articles are used very often, and here each noun keeps its own article.

The sentence shows that they are masculine because it uses el with both of them:

• el regloscopio
• el frenómetro

Also, many nouns ending in -o are masculine, though not always.
And nouns ending in -metro are typically masculine too:

• el termómetro
• el kilómetro
• el cronómetro

So frenómetro being masculine is very unsurprising.

Because comparar X con Y is a normal and very common structure in Spanish.

So:

• Comparar el regloscopio con el frenómetro = to compare the regloscope with the brake tester

This is very close to English compare X with Y.

Spanish also sometimes uses comparar X y Y:

• Comparamos el regloscopio y el frenómetro.

That can also mean we compare the regloscope and the brake tester.

But comparar X con Y is especially clear and explicit.

Yes, sometimes Spanish uses comparar X a Y, but comparar X con Y is generally the safer and more common choice for learners.

Very broadly:

• comparar X con Y = compare X with Y
• comparar X a Y can appear in more literary or rhetorical comparisons

For everyday practical Spanish, especially in a technical sentence like this one, con is the most natural choice.

Because the personal a is mainly used before specific human beings (and sometimes pets or personified beings), not ordinary inanimate objects.

Here, both things are objects/instruments:

• el regloscopio
• el frenómetro

So no personal a is needed.

Compare:

• Veo el coche. = I see the car.
• Veo a María. = I see María.

The basic word order here is very normal:

• Comparamos
  • direct object
    • con phrase

So:

• Comparamos el regloscopio con el frenómetro.

This is the most straightforward order.

You could change the order in some contexts for emphasis, but the standard version is best for learners.

For example, in marked or literary language, you might move things around, but in ordinary Spanish this sentence is perfectly natural as it is.

It is pronounced roughly like:

• kohm-pah-RAH-mohs

The stress is on ra:

• co-mpa-RA-mos

This follows normal Spanish stress rules, so it does not need a written accent mark.

Frenómetro is pronounced roughly like:

• freh-NOH-meh-troh

The stress is on nó.

It has a written accent because, without the accent mark, normal spelling rules would place the stress elsewhere. The accent mark shows that the stressed syllable is nó:

• fre-NÓ-me-tro

This is similar to:

• termómetro
• barómetro
• cronómetro

Because its stress already follows the normal Spanish stress rules.

It is pronounced roughly:

• reh-gloh-SKOH-pyoh

Since the stress naturally falls where Spanish spelling rules predict it should, no written accent is needed.

So the difference is:

• regloscopio — no accent mark needed
• frenómetro — accent mark needed to show irregular stress

Yes, that is possible.

It would mean something like:

• We compare the regloscope and the brake tester

Using y simply links the two items as the two things being compared.

Using con makes the relationship especially explicit:

• Comparamos el regloscopio con el frenómetro.

Both can be correct, but comparar X con Y is especially common and clear.

It can be, yes — but not only that.

Comparamos can be:

• present indicative: we compare
• preterite: we compared

So the form alone does not tell you which tense is intended. You need context, time words, or the surrounding sentences.

It is a simple declarative sentence with:

• an implied subject: (nosotros)
• a verb: comparamos
• a direct object: el regloscopio
• a prepositional phrase: con el frenómetro

So the structure is:

• (We) compare the regloscope with the brake tester.

That makes it a very useful model for building similar sentences:

• Comparamos el coche con la moto.
• Comparamos el sistema antiguo con el nuevo.

Usually at the beginning:

• Nosotros comparamos el regloscopio con el frenómetro.

That is the most natural place.

You might do this if:

• you want contrast
• you want clarity
• you want emphasis

For example:

• Ellos analizan los resultados, pero nosotros comparamos el regloscopio con el frenómetro.