| short | shorter | shortest |
| tall | taller | tallest |
| small | smaller | smallest |
| big | bigger | biggest |
| high | higher | highest |
| thick | thicker | thickest |
a) The Mekong River is long . The Amazon River is longer than the Mekong . The Nile is the longest river in the world
b) The Great Wall of China is long . It is the thickest structure in the world
c) Sears Tower in Chicago is tall , but it isn't the tallest building in the world . PETRONAS Twin Towers in Kuala Lumpur is taller than Sears Tower . It is the tallest building in the world
d) Hanoi is big , but is isn't the biggest city in Viet Nam . Ho Chi Minh City is bigger than Hanoi . It is the biggest city in Viet Nam . But Mexico City is the biggest city in the world