Hi Pramod Kumar! It (something) could be given (to someone) today or tomorrow. This one reflects the present and future. E.g. The homework could be given to Philip today/tomorrow if he is so desperate for it. It (something) could have been given (to someone). This one reflects the past. E.g. The homework could have been given to Philip yesterday, as that's when he needed it the most. I hope it helps.

The very good answer just given here still applies: https://www.italki.com/question/501602 The opportunity for 'giving' still exists with 'could be given'. The opportunity (for 'giving') has passed and it's now gone for 'it could have been given'.

well both of these are talking about "possibility" "it" could be given - this is an uncertain reference to something that may or MAY NOT be given to someone or something, or perhaps may or may not be inclined to something. "this could be given to anyone" - whatever this thing is you COULD give it to anyone you want. OR maybe it's talking about being inclined or prone to something "He could be given to fits of rage" - talking about someone who MAY or MAY NOT get very angry very suddenly about things. could have been given - This is now in the past tense and is thus even less certain now but still applies in many of the same ways. "I could have given that cake to anyone, but i gave it to you" - I'm talking about the possibility of me giving the cake to someone else, but the reality that i gave it to you.

well both of these are talking about "possibility"