Learn Portuguese (Portugal): Já que temos o equipamento, testamos a amostra. - Since we have the equipment, we test the sample.

Já que translates to "since" or "given that". While porque also means "because", it is usually placed in the middle of a sentence. Causal conjunctions like já que, visto que, and dado que are much more natural when you want to put the reason at the very beginning of the sentence to set the context.

Can I swap já que for visto que or dado que in this exact sentence?

Yes, they are entirely interchangeable here! Visto que (seeing that) and dado que (given that) would also work perfectly. Já que is slightly more common in casual everyday speech, while dado que sounds a bit more formal, but their grammatical function is exactly the same.

Does já que require the subjunctive mood for the verb ter?

No, it takes the normal indicative mood. Because causal conjunctions like já que introduce a known fact or an established reason (the fact that we already have the equipment), you just use the regular present tense temos rather than a subjunctive form.

Is testamos in the present tense or the past tense?