Why is a river so rich ?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

What has many keys but can’t open a single lock?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What has many teeth, but cannot bite?

There are three houses in a straight row. One is red, one is blue, and one is white. The red house is left of the middle. The blue house is right of the middle. Where's the white house?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

A man has to get a fox, a chicken, and a sack of corn across a river.

He has a rowboat, and it can only carry him and one other thing.
If the fox and the chicken are left together, the fox will eat the chicken.
If the chicken and the corn are left together, the chicken will eat the corn.

How does the man do it?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?