When 2 is written in its binary form or when minute hand of a clock is towards 2

Bellybutton.
Or it can be Father, Mother, Grandfather, Grandmother etc.

The third Logician can  Answer with ‘Yes’

The first person answered ‘I don’t know’ because he wants to drink and he  was not sure about others, If he himself not wants to drink he should have answered with ‘No’
Same was the case of the Second logician
For the Third logician, he only needs to consider whether he wants a drink or not. because from the answers of other logicians he gets to know that others want to drink.
So he can answer with either ‘Yes’  or ‘No’ depending on whether he needs the drink or not.

Downwards

When he opened the eyes, the train was in a tunnel, and it was dark inside the train. So he thought that he does not get the eyesight after the operation. So he decided to commit suicide.

Since you are coming from Chesterton. you can put the sign back by putting it in such a way that the Chesterton sign points to the direction you are coming from.

ZERO.

if there is at least  one person with no fingers in the hand,

9 People.

Mr. and Mrs. King ->2
Daughters                 ->6
Son                                ->1
——————————
Total                                    9

Guardians of the Galaxy.

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