How can you make number one disappear by adding something to it?

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?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

What four weights can be used to balance from 1 to 30 pounds?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?

All of the flowers I have are orchids except two. All of the flowers I have are hibiscuses except two. All of the flowers I have are roses except two.

Can you tell me how many flowers I have?