Se puede nadar en este lago.
It is an impersonal sentence because it has no subject. This case is used "<u>se</u>", it is when we want to talk about the subject.
<h3><em><u>MissSpanish</u></em></h3>
Answer:
yo pido (affirmative) yo no pido (negative)
Explanation:
you may or may not need the yo