Very difficult riddles

There was a man who was born before his father, killed his mother, and married his sister. Yet, there was nothing wrong with what he had done. Why?

What is the difference between a school boy studying and a farmer watching his cattle?

A boy has as many sisters as brothers, but each sister has only half as many sisters as brothers.
How many brothers and sisters are there in the family?

What is the next 3 letters in this riddle? o t t f f s s _ _ _

Suppose you want to send in the mail a valuable object to a friend. You have a box which is big enough to hold the object. The box has a locking ring which is large enough to have a lock attached and you have several locks with keys. However, your friend does not have the key to any lock that you have. You cannot send the key in an unlocked box since it may be stolen or copied. How do you send the valuable object, locked, to your friend – so it may be opened by your friend?

t’s always 1 to 6,
it’s always 15 to 20,
it’s always 5,
but it’s never 21,
unless it’s flying.

Ben walked into a hardware store and asked the price of some items. The salesman said: One costs $1, Eight costs $1, Seventeen cost $2, One hundred four costs $3 and One thousand seventy two costs $4. What was Ben buying?

Marking mortal privation, when firmly in place. An enduring summation, inscribed in my face.
What am I?

I’m one of five, I’m not alive. The one who sent me forth became king, The one who received me died.
What am I?

I move very slowly at an imperceptible rate, although I take my time, I am never late. I accompany life, and survive past demise, I am viewed with esteem in many women’s eyes.
What am I?

An alarm clock runs 4 minutes slow every hour. It was set right 3 1/2 hours ago. Now another clock which is correct shows noon.
In how many minutes, to the nearest minutes, to the nearest minute, will the alarm clock show noon?

I’m a word that’s hardly there. Take away my start, and I’m an herbal flair. What am I?

You want to send a valuable object to a friend. You have a box which is more than large enough to contain the object. You have several locks with keys. The box has a locking ring which is more than large enough to have a lock attached. But your friend does not have the key to any lock that you have. How do you do it? Note that you cannot send a key in an unlocked box, since it might be copied.

Peter celebrated his birthday on one day, and two days later his older twin brother, Paul, celebrated his birthday.
How could this be?

My first is a creature whose breeding is unclear. My second, a price you must pay. My whole can be found in the river of Time and refers to events of today. What am I?

Marco and Bob have been the best friends ever since they were little kids. They are also very competitive. Throughout the years they have challenged each other to do both physical and mental challenges. And they completed the challenge. But one day Marco thought of something to challenge Bob to do – something he could start but never finish. The average man could do it and so could Mark and they were both the same sex and the same size. It is a physical challenge. Can you figure out what it was?

What has four fingers and a thumb, but is not living?

I have keys but no locks. I have a space but no room. You can enter, but can’t go outside. What am I?

I can only live where there is light, but I die if the light shines on me. What am I?

What flies when it’s born, lies when it’s alive, and runs when it’s dead?

What gets wet when drying?

Every night I’m told what to do, and each morning I do what I’m told. But I still don’t escape your scold.

Give me food, and I will live. Give me water, and I will die. What Am I?

What comes once in a minute, twice in a moment, but never in a thousand years?

I am a mother and a father but have never given birth. I’m rarely still, but I never wander. What am I?

Hurt without moving. Poison without touching. Bear the truth and the lies. Are not to be judged by our size. What are we?

Which word in the dictionary is spelled incorrectly?

I’m always there, some distance away. Somewhere between land or sea and sky I lay. You may move towards me, yet distant I stay.