7. How many main parts does the space shuttle have?
8. What part of the shuttle actually goes
into space?
9. How does the design of the shuttle
make it a kind of space plane?
na

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.