A They don't need their owners'attention. B They are emotionally attached to their owners. C They don't experience separation anxiety as dogs do. D They respond to their owners'voices less than dogs do.

A Cats take food no matter who feeds them. B Cats refuse food from unhelpful strangers. C Dogs refuse food from those who anger them. D Dogs take food no matter how they are treated.

A To treat them as friends. B To compare them with dogs. C To regard them as animals. D To care about their behavior.

A By improving attention. B By slowing memory loss. C By connecting with others. D By controlling cell growth. E

A By increasing the brain size. B By decreasing the protein level. C By extending the time of concentration. D By strengthening brain cells'connections.

A Babies'ability to focus. B Babies'mastery of skills. C Babies'muscle strength. D Babies'near-constant movement.

A Exercise strengthens people's body. B Exercise helps babies to grow. C Exercise improves people's life. D Exercise benefits the brain.

A The Indian women fighters. B The head of an Indian tribe. C The first explorer of the river. D The women fighters in ancient Greek stories.

A The Amazon basin is the largest in the world. B The Amazon River causes huge rains every summer. C The Amazon rainforest supports about 20%of the world's plants. D The Amazon River carries 75%of the world's water to the oceans.

A They both absorb light. B They both store heat. C They both help plants grow. D They both cause global warming.