A、Their liveliness. B、Their intelligence. C、Their tricks. D、Their order. A此题考的是对第一段大意的理解，最后一句话是此题的原句Their liveliness makesthem f

Monkeys are small lively mammals that rank high among the most intelligent animals. Scientists classify monkeys in the highest order of mammals. Because monkeys are so intelligent, they can learn many tricks. Their liveliness makes them favorites among zoo visitors.
    The New World monkeys, one of two major groups of monkeys, live in Central America and Africa. The nostrils of New World monkeys are spaced more widely than those of the Old World monkeys. Most kinds of Old World monkeys have 36 teeth. All New World monkeys have 32 teeth. Some New World monkeys can hold things with their tails but no Old World monkeys can.
    Monkeys use their long arms and legs to help them climb and leap. They grasp the branches of trees with their hands and feet. Most types of monkeys have a long tail that helps them keep their balance. While moving through trees, some monkeys use their tails to grasp branches.
    Almost from the moment of birth, a baby monkey hangs on to its mother by grasping her fur. The infant clings to its mother’s underside at first. Later it rides on her back. Until the baby can travel safely on its own, its mother carries it. A baby monkey feeds on its mother’s milk. Depending on the species, a baby monkey receives its mother’s milk for a few weeks up to two years.
Questions 16 to 18 are based on the passage you have just heard.
16. What makes monkeys favorites among zoo visitors according to the speaker?
17. What is true of New World monkeys?
18. What do most types of monkeys use their long tails for?