People have different ways of greeting each other. They might shake hands  , kiss or hug  . But do you ever wonder how dogs say hello? If you are a dog lover, you already know the answer to this question. When you arrive home, your dog jumps up into your lap  . It wags   its tail, and sometimes gives you wet kisses. Like humans, dogs have five senses  : smell, touch, sight, hearing and taste. Humans use sight as the main sense for recognizing   one another. But dogs have poor eyesight. They use smell to recognize others. A dog's sense of smell is much better than a human's. It is through its sense of smell that tells the differences between different people. Dogs use smell to recognize other dogs, too. They tell the differences by the smell of pee   and pooh  . When two dogs meet, they smell each other's noses. Then they go side to side, and smell each other's butts  . By smelling its friend's behind, a dog knows who it is with. That is also why dogs smell everything they can on the road. By smelling grass, trees and signposts  , dogs know which other neighborhood dogs have been around. People have different ways of greeting each other except   _  .
hug shaking hands jump kiss