People are interested in animal communication and scientists have done lots of researches on this subject.
Most animals always use language to communicate. If cats look and blink （眯眼）at you slowly, which shows their love to you. You can also do this show you love. When they sit with tails around themselves, they're happy. If they feel scared, their tails may look like the end of toilet brushes. When they put ears back, they are a bit mad. Birds can also show feelings through eyes and feathers. If birds make their pupils（瞳孔）large and small from time to time, this can be a sign that they are excited or scared or angry. Birds will ruffle（弄乱） their feathers when they clean themselves. However, if their feathers remain ruffled, it may mean they are ill. You'd better take them to see aveterinarianin an animal hospital.
Some animals communicate by smell. Dogs are famous for this. They can learn about something by smelling. They can find missing people by using their fantastic sense of smell. They have helped the police for a long time. Mice have an excellent sense of smell, too. Scientists even train them to find landmines（地雷）.It is found that even ants use smell, they use smell to tell other ants where the food is.
Frogs and insects communicate with sounds. Usually the "gentlemen" make sounds to invite the "ladies". Whales and elephants also use sound to communicate, these sounds can travel very far through water or the ground, but it is not possible for humans to hear some of the sounds.
Learn more about the ways of animal communication at http://www.animal.com.cn.
