5. 指代题

练习题：

（1）        When small fish venture too close to the tentacles of these "living flowers", they are stung and eaten.

（2）        The male seals do not journey so far. They swim only to the islands and there the cycle begins again.

（3）        The mountain's summit is broad and rounded. It is 14,410 feet above sea level and has an area of about one square mile.

（4）        Although wagon trains had been used to haul freight and passengers between the  Eastern seaboard and the Ohio Valley since 1812, they were first used extensively in the 1820's on the Santa Fe Trail.

（5）        The clownfish even builds its nest where the anemone can protect it.

（6）        X-rays allow art historians to examine paintings internally without damaging them.

（7）        Florists often refrigerate cut flowers to protect their fresh appearance.

（8）        Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds.

（9）        Some skilled craftspeople made intricately carved wooden ornamentations for furniture or architectural decorations, while others carved wooden shop signs and ships' figureheads.

（10）    Many adults, poor and disillusioned with farm life, were lured to the cities by promises of steady employment, regular paychecks, increased access to goods and services, and expanded social opportunities. Others were pushed there when new technologies made their labor cheap or expendable.

（11）    Some species, for example, begin by dropping the outermost primary feathers on each side and wait until the replacement feathers are about one-third grown before shedding the next outermost, and so on. Others always start with the innermost primary feathers and work outward.

（12）    The principal difference between urban growth in Europe and in the North American colonies was the slow evolution of cities in the former and their rapid growth in the latter. In Europe they grew over a period of centuries form town economies to their present urban structures. In North America, they started as wilderness communities and developed to mature urbanism in little more than a century.

（13）    The energy content of food is stored in the chemical bonds that link its atoms and molecules.

（14）    In the past, biologists considered mushrooms and other fungi as a type of non-free   plant. Today, however, they are most commonly regarded as a separate kingdom of living things.