These types of puzzles are known as charades. What you have to do is to find two words that are referred to in the first stanza and the second stanza and put them together to form the third word in the third stanza.

Just for example, if my first refers to 'off' and my second refers to 'ice', then my whole will be the 'office'.

My first is present - future's past -
A time in which your lot is cast.

My second is my first of space
Defining people's present place.

My whole describes a lack of site -
A place without length, breadth, or height.

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

A man died and leaves Rs.10,000 in his will. There are 6 beneficiaries- his 3 sons and their wives. The 3 wives receive Rs.3960 of which Priyanka gets Rs.100 more than Tanu and Neha gets Rs.100 more than Priyanka.
Pramod gets twice as much as his wife, Tushar gets the same as his wife, and Prashant gets 50% more than his wife.

Who is married to whom?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Why is it very easy to weigh a fish?

What number should come in place of the question mark below?

If an electric train is travelling south, then which way is the smoke going?

Prove that twice of ten is the same as twice of eleven.

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?