Can you please look at this short website:
The Impersonal and Passive se in Spanish
The website makes the statement:
Impersonal voice using se will use a singular verb since the se can be replaced by uno ("one").
If I am reading that instruction correctly, and I want to translate the English
One can see many stars, on a clear night., then either (1) or (2) is OK.
1) "Se puede ver muchas estrellas, en la noche clara."
2) "Uno puede ver muchas estrellas, en la noche clara."
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As a secondary question, I was under the impression that the passive voice in Spanish
must involve the use of a conjugation of
ser in the present indicative and a past participle of some verb. Is that correct? That's the way it is in English.
If that is the case, and I want to say
Many Stars can be seen, on a clear night. then I must have a conjugation of ser and viendo in the sentence.