How many words can a pen with half refill write?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

Find out the missing number in the picture attached:

Name the three-letter word that can complete the below words?

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E

What have one eye but still cannot see?

What breaks yet never falls, and what falls yet never breaks?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?

A very interesting trivia question for all.

Why do men's shirts have their buttons on the right side and women's have buttons on the left-hand side?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?