It’s always awkward when you meet someone from a different country．You never know whether to shake hands, bow or even whether to kiss on the cheek．But what if you were a dog?
If you are a dog owner, you must be familiar with how your dog says hello to you．Seconds after you arrive home, your dog jumps up on you．You come face to face with a tail-wagging, wildly excited ball of fur that can’t get enough of you．If you’re not happy with that, it will shower you with wet “kisses” perhaps ruining your best shirt．
Like humans, dogs have five senses: smell, touch, sight, hearing and taste．
Unlike humans, dogs use smell rather than sight to identify others around them．A dog’s sense of smell is thousands of times better than that of humans．Your dog can’t just tell what a human being smells like, but it can also tell the difference between different members of its human family by their smell．
They also greet each other this way, not eye to eye, but nose to nose．
To be precise, when they first meet each other, they start with a quick sniff of each other’s noses．Then they will go side to side, working their way towards the back end．
Dogs smell everything they can during a walk．They sniff grass, bushes, trees and signposts．By doing this, dogs know not only what they are looking at, but which other neighborhood dogs have been around lately．
So next time you see your dog sniffing the wrong end of another dog, don’t regard it as a bad habit．They are greeting each other．（295 words）
68．What is the main idea of the passage?
A．It tells readers how to take good care of dogs．
B．It tells readers what to do to make dogs happy．
C．It tells readers how dogs greet others．
D．It tells readers what dogs do to amuse owners．
69．The 2nd paragraph is written mainly to tell readers ____．
A．how dogs greet their owner B．that dogs like jumping up on people
C．that dogs enjoy ruining their owners' shirt D．how dogs show their love
70．How does a dog say hello to another one?
A．By sight． B．By both sight and smell．
C．By smell． D．By sight and touch．