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Hi, my question is: when using a verb as the subject of a sentence, so as a noun, what form of the verb should one use?
That is, should one use the to+infinite form or the infinite+ing form?
This example should clarify what I mean:

Which one of the following sentences is correct?

1. To think of the moon as a star is wrong
2. Thinking of the moon as a star is wrong

I would also like to ask you: which one of these expressions is correct?

1. In the moment in which it happened
2. In the moment when it happened

Thanks for your help
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First question: both are correct

Second question: A contextual sentence would help.

I was in the bath at the moment it happened.
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These are all OK:

In/At the moment in/at which it happened, he immediately ran away-- as Philip indicated, 'at' is much better for a moment-- which is only momentary. This one also seems vaguely redundant.
In/At the moment when it happened, he immediately ran away
In/At the moment it happened, he immediately ran away

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So, both forms in the second questions are wrong?
That is, these two are wrong:

In the moment in which it happened, he immediately ran away
In the moment when it happened, he immediately ran away

while this one is correct:

In the moment it happened, he immediately ran away

?

Thanks
 Mister Micawber's reply was promoted to an answer.
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Mister Micawber.
These are all OK:

In/At the moment in/at which it happened, he immediately ran away-- as Philip indicated, 'at' is much better for a moment-- which is only momentary. This one also seems vaguely redundant.
In/At the moment when it happened, he immediately ran away
In/At the moment it happened, he immediately ran away

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Sorry, which sentence is redundant? Also, can I do a mix of what you wrote? For instance:
In the moment at which it happened...

thanks
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I said that the first sentence seems vaguely redundant. I'm not sure that it is, but it is certainly awkward. Yes, you can mix those prepositions as far as I'm concerned.
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