1.complete the sentences with the correct forms of the verbs in brackets.
   Inside your head is a remarkable  organ, the brain. You use it to understand and remember things that  1______(happen) around you.
 The brain is soft and spongy.It 2______  (make) of billions of tiny parts called cells. Three coats or membranes 3________  (cover) the brain.
 The brain sometimes 4___________  ( call)  the  busiest commu nication centre in the world. The brain 5__(control) your  body functions and keeps all parts of your body working together. Thousands of messages from all parts of the body 6______(send) to and from the brain. Messages 7_____ (carry) to the brain  by  sensory nerves. Special places, or centres, on the brain receive sensory message from all parts of the body. When message 8__ ___            (receive) by centres, the brain 9____(interpret) them.
  All day long your muscles and your brain 10______(work).