How do you usually take a message for others? By phone, by e-mail or just by talking with them? An Englishman named Zack finds ________ interesting way. He has a special post office at his home.

Zack ________ a cat named Billy. It often goes out to play. Many people think it is cute. When they meet the cat on the street, they always stop ________ with it for a moment.

Billy wears a collar (颈圈). Every time it goes back home, Zack can ________ some notes on it. Those are the ________ from people in his neighborhood. “Your cat often sits and meows (猫叫) outside ________ home,” one of the messages reads. “I love it and let it in.”

Now ________ people know Billy. It takes home many messages every day. They are ________ everything from cooking to movies. ________ wrote these messages? Zack doesn’t know, ________ he writes back to every one of them. Thanks to the cat, Zack has an interesting life in the neighborhood.

A BBC documentary(纪录片) shows animal relationships in a special way, more closely than ever before.

Spy in the Wild (《荒野间谍》) is a documentary. The video team sent 34 robot animals into the ________. They look and move like real animals, but in fact they are spy robots with ________ inside them.

A wild spy dog was sent to the grasslands of Africa. The spy dog first ________ to other wild dogs as a way of saying, “I am friendly.” This allowed him to be accepted ________ by the group.

A spy monkey became ________ with real monkeys after living with them for a month. One day, he ________ from a tree. All the other monkeys thought he died. They were so sad that they surrounded(围绕) his “body”. One ________ hugged the “body” of his robot friend.

However, not all of the newcomers were welcomed. The spy squirrel(松鼠) wasn’t so ________. The real squirrels first stole his food, and then they ________ his camera, too. Animals can be more like humans than you might think. They have ________ of love, friendship and anger, just like we do.

With the help of the spy animals, the documentary lets us explore the wildlife world.