(1) feel + ... + to-infinitive: She felt his answer to be evasive.
(2) feel + ... + bare infinitive: She felt him keep something back.
I have been trying to find the rule: when "feel" must be used with to-infinitives and when with bare infinitives. Do you know it?
The only one I could find: we must use "to" only before "be", and before all other verbs we cannot use "to". Is it right?