Study, observe, listen.
The universe operates under certain observable laws. As intelligent creatures, we are capable of understanding these laws. Even then, our understanding changes. One must be open to reality and how understanding can change.
More truthful and most truthful, respectively.
No, it is not an adverb. Truthful is an adjective, and the adverb form is "truthfully."
yes it is truthful.
More truthful
"you are not truthful"
He was truthful as he explained what had happened. She was not truthful as she attempted to frame him for the crime.
yes he is very truthful
My sister is really truthful.
The noun form of the adjective 'truthful' is truthfulness.The word 'truthful' is the adjective form of the noun truth.
The jury believed the defendant's statement was truthful.
I was most truthful thsn her
The opposite of truthful is deceitful or dishonest.