If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

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?

You see me once in June, twice in November, and not at all in May. What am I?

Why is a river so rich ?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

What animal walks on four legs in the morning, two legs during the day, and three legs in the evening?

Oedipus, the king of Thebes, figured out the answer to the riddle:

The measurement of time, That can't be found on a clock, But can be looked upon on a map.

Who is He ?

There is a circular car race track of 10km. There are two cars, Car A and Car B. And they are at the exact opposite end to each other. At Time T(0), Both cars move toward each other at a constant speed of 100 m/seconds. As we know both cars are at the same speed they will always be the exact opposite to each other.
Note, at the center, there is a bug which starts flying towards Car A at time T(0). When the bug reaches car B, it turns back and starts moving towards the car A. The speed of bug is 1m/second. After 5 hours all three stop moving.
What is the total distance covered by the bug?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?