Bears vary as much in character and habits as they【C1】______ in size. Although a few kinds

, such as grizzlies and polar bears, are fierce, most are【C2】______ and only become violent when their food supplies or young are【C3】______ . 【C4】______ to common belief, they will not hug victims to death. They are usually quiet【C5】______ when feeding or when challenged by other bears.

Except during the mating season, bears live【C6】 ______ lives. They prefer to roam in areas【C7】______ by humans. Most tend to stay within certain【C8】______ Black bears,【C9】______ , usually stay within an area of about 14 square miles (36 square kilometers). Although they remain【C10】______ a particular range, most bears do not have a【C11】______ resting place, preferring【C12】______ to wander.

Despite the fact that bears in the wild are used to【C13】______ , most of them can【C14】______ easily to life in captivity. Zookeepers agree that bears are【C15】______ the shrewdest and most【C16】______ of animals kept in zoos. Performing bears have been popular features in【C17】______ since the Middle Ages. They can be taught such tricks【C18】______ wrestling and boxing, dancing, blowing a bom, riding a bicycle, and sliding on a toboggan.

Survival in the wild can be【C19】______ for bear cubs. They begin life as hairless, extremely small, and helpless creatures【C20】______ to open their eyes for about a week. A 200-pound (90-kilogram) black bear may have cubs weighing only 8 ounces (230 grams ) each. Even a newborn grizzly weighs only about 1 pound (0.5 kilogram) and measures only 9 inches (23 centimeters) from the tip of the nose to the tip of the tail. There are from one to four, but usually two, cubs to a litter born anytime between November and March.

【C1】

A．do

B．are

C．can

D．grow