2) Dogs Many experts think that around 20,000 years ago, wolves and humans started to live side by side. Over time, some wild animals became tamed. For example, wolves chased away dangerous animals. They ate food that humans A _______ away. Dogs B _______ humans' friends by accident. One of the reasons is that dogs are C _______ than other animals. They can D _______ quickly. Most dogs learn new behavior in just four tries. If you have a dog, think of a new trick and try to teach it to do it. Keep the instruction enjoyable for the best results. When your.dog E _______ a command. A) THROW B) NOT BECOME C) CLEVER D) LEARN E) DO Keys: A) threw/used to throw/usedtothrow/would throw/wouldthrow, B) didn't become/did not become/didnotbecome, C) cleverer/more clever/moreclever, D) learn, E) does