Best riddles with simple answers

I have four legs and a tail. I have no teeth. I can swim and dive underwater. I carry my house around with me. I am a...

If I have it, I don't share it. If I share it, I don't have it. What is it?

What always runs, but never walks, often murmurs, never talks, has a bed, but never sleeps, has a mouth, but never eats?

I have no legs. I will never walk, but always run. What am I?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

I am not alive but I grow. I don't have lungs but I need air. What am I?

What can run but can't walk?

What is the shortest complete sentence in the English language?

The beginning of eternity, The end of time and space. The beginning of every end, And the end of every place.

I live in lakes and rivers. I eat fish and birds. I have four legs and a long tail. I have lots of pretty teeth. I am a...