Hello, UM Chakma.
I can understand your confusion.
I think you are referring to Q9 and Q12 here.
I personally do not agree with the answer to Q12. The answer is 'True' in my opinion.
Let's wait for some native speakers to respond.
(Edit) If the question is intended to mean "We can use the structure - very + adjective + infinitive without to", then the answer would be 'False'.
"very + adjective + to-infinitive" is OK, as in
I'm very happy to know you'll come back.