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?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

What has 88 keys?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

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

What runs around the whole yard without moving?

It is always ahead of me yet I can never see it. What is it?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What is so fragile that saying its name breaks it?

What can you catch but never throw?