A、Dogs and cats. B、Monkeys and snakes. C、Fish and mice. D、Wolves and dogs. B

Americans love pets. Many pet owners treat their pets as a part of the family. You might say Americans treat their pets like they treat their children—sometimes even better. In America, there are more households with pets than those with children. At least 43 percent of US homes have pets of some sort. Exotic creatures, such as monkeys, snakes and even wolves find a home with some Americans. More common pets include fish, mice and birds. But the all-time favorites are cats and dogs, even at the White House. Many grocery stores in America sell pet foods. Pets can even accompany their owners on vacation. Fancy hotels are beginning to accommodate both man and animal. Animal guests at Four Seasons Hotels can enjoy delicious meals served on fine china and sleep in soft beds. The average American enjoys having pets around, and for good reason. Researchers have discovered that interacting with animals lowers a person’s blood pressure. Dogs can offer protection from robbers and unwelcome visitors. Cats can help rid the home of unwanted mice. Little creatures of all shapes and sizes can provide friendship and love. In many cases, having a pet prepares a young couple for the responsibilities of parenthood. Pets even encourage social relationships: They give their owners an appearance of friendliness, and they provide a good subject of conversation.
19.  What kinds of pets are less common in America?      
20.  What can we know about Four Seasons Hotels?      
21.  What is one of the benefits of having pets?