Riddles

What month/s of the year have 28 days?

I start with T end with T and am full of T

What month do people sleep the least?

What has many keys, but can't even open a single door?

What is often returned but never borrowed?

What flies when it is born, lies when its alive, and runs when its dead?

What is as fast as a cheetah as slow as a turtle and can transform into any shape or object?

What English word has three consecutive double letters?

A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many brothers and sisters are there in the family?

You see a boat filled with people. It has not sunk, but when you look again you don’t see a single person on the boat. Why?