You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

What has to be broken before you can use it?

If an electric train is travelling south, then which way is the smoke going?

What have one eye but still cannot see?

How can you take 2 from 5 and leave 4?

I am soft and cuddly that soothe your heart. But, If you pick my last name I am going to tear you all apart. Who am I?