O_er_t_o_

Complete the missing letters of the given word.

There are five men, let's say Tarun Harish Lavesh, Manoj, and Manish. All of them have a dot mark on their forehead. They can't see the dots on their forehead but can see the ones on others. The owner of WHITE Dot is an honest person and will never lie, while the owner of BLACK Dot always tells the lie.

This is the statement from Tarun Harish Lavesh and Manish:
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'

What colour is the dot on each of Tarun Harish Lavesh, Manoj, and Manish's forehead?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Complete the table series riddle by finding the number that can replace "??".

Move four matchsticks to the below square to form three squares?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

A couple went on a climbing trip. But only the husband returned from the vacation and said that his wife slipped off while climbing and died. On investigating, the local sheriff arrested him saying, 'Your travel agent called. You murdered your wife.'

The man did not inform anyone about the trip. Then how was the agent so sure that it was a murder?

I am written with two letters.
I said with the one.
I usually am seen with the two.

Who am I?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?