Can anyone tell me a word in the English dictionary which has a silent 'z'?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

What is always in front of you but can’t be seen?

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

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

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

What two things can you never eat for breakfast?

A horse was tied to a rope 5 meters long and the horses food was 15 meters away from the horse. How did the horse reach the food?

Jack and Joseph are well-known golf rivals. One Day during a match, they were level at a score of 30. Jack hit a bad shot and Joseph added 10 to his score. Joseph then hit an awesome shot and he won the game.

How ?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing.

Why?