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 are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

What does this mean?

CCCCCCC

Why do we preferably have round manhole covers and not square ones?

A game is being played where eight players can last for thirty-five minutes. Six substitutes alternate with each player in this game. Thus, all players are on the pitch for the same amount of time including the substitutes.

For how long is each player on the pitch?

If I put in one bird per cage, I have one bird too many. If I put in two bird per cage, I have one cage too many. How many cages and birds do I have?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?

Can you find out the number that should replace the question mark with a valid reason?

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?