Add the missing comparatives and superlatives.

   bigger      biggest      older      oldest      smaller      smallest      taller      tallest      younger      youngest  
  1. Tom is tall. Sam is than Tom, but Charles is the of them.
  2. Sue is young. Henry is than Sue, but Alexander is the .
  3. My brother is old. My father is than his son, but my grandfather is the .
  4. A guinea pig is small, a rat is than a guinea pig, but an ant is the .
  5. A lion is big, a bear is than a lion, but the elephant is the .