Using である in the middle of a sentence?

Question

I was wondering, when writing something like 「〜だと思う」should I keep it as だ or say 「であると思う？」Would both work? Thanks so much!!

Answer 1

Both work fine as far as grammar.

The only difference between 「～～だと思{おも}う」 and 「～～であると思う」 is that the former sounds more informal than the latter.

We use the former most of the time in our everyday kind of informal speech.