Ask Mr Brain . . . all will be explained
What is the Pentagon?
It is the headquarters of the United States Department of Defence for army, navy and air force services. It is a large five-sided building in Arlington county in Virginia, near Washington, DC.
On its completion in 1943, it was the world's largest office building, covering 14 hectares and offering 343,730 square metres of floor space for as many as 25,000 people.
The building consists of five pentagons (a shape with five sides). The five 'rings' have 10 spoke-like corridors connecting them.
A huge concourse within it provides a shopping centre for Pentagon workers. Parking areas around the building can accommodate as many as 10,000 cars. A heliport was added in 1956.
How do ballerinas dance on their toes? Doesn't it hurt?
When you watch a ballet, one of the most beautiful things is to see the ballerinas float gracefully across the stage on their toes.
They do this with the help of strong muscles and special shoes called pointe or toe shoes.
Pointe shoes are built from layers of canvas and glue with a hard box that forms the tip of the shoe. They have thin leather soles and are covered with pink satin. The shoes are designed to give support to the arch of the foot and most importantly, the dancer's toes.
Pointe shoes do not last long. Some ballerinas wear out several pairs in a performance.
Even with the right shoes to pro tect her feet, a ballerina must have spent many years learning to balance and dance on her toes, and have strong muscles in the legs, feet, lower back and pelvis.
A ballerina's training should start at an early age, between eight and 11 years old. At about 11 or 12, girls will start to learn to balance on the front part of their toes (en pointe) and train up their muscles to dance in this position.
Professional dancers are athletes and often train seven hours a day, six days a week, or even longer on performance days.
Even though ballerinas have practised long, dancing en pointe still hurts. Many ballerinas place lamb's wool or paper towels to cushion the toes.
So next time you see a ballerina on her toes, remember to clap loudly because she has worked very hard to get there.
Who is a middle-aged person?
A middle-aged person is generally defined as being between 40 and 60 years old - an adult before the onset of old age. At this age, there begins a gradual decline of physical abilities. If looked at constructively, middle age can prepare an individual for a satisfying and productive old age.