1. I think we are here to talk truly.

Question

2. I think we are here to talk truthfully.
3. I think we are here to talk t______

(Are they all grammatical and the same? What other adverbs can we use starting the letter t?

Answer 1

I wouldn't use 1, but 2 works fine.

You could also use these adverbs:

frankly
openly
honestly

Others can be found by looking up these three plus "truthfully" in a thesaurus.