The diagrams below show the life cycle of a species of large fish called the salmon.

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问题 The diagrams below show the life cycle of a species of large fish called the salmon.

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答案Salmon begin life as eggs on a pebbly riverbed, hidden among reeds in the slow-moving upper reaches of a river. After five to six months the eggs hatch into ’fry’. For approximately the next four years, these baby salmon will live in the lower, faster-flowing waters of their river. During this time they measure between three and eight centimetres in length. By the time salmon reach twelve to fifteen centimetres, they are termed ’smolt’, and at this time they migrate further downriver into the open sea. After five years at sea the salmon will have grown to adult size, which is between seventy and seventy-six centimetres. They then begin swimming back to their birthplace, where they will lay their eggs, and the cycle starts anew. In summary, the salmon passes through three distinct physical stages as it grows to maturity. Each of these stages takes place in a very different aquatic location. It is noteworthy that the first two stages of this fish’s life occur in a freshwater environment, while the third stage is lived in saltwater.

解析 由题目可知,本图是一种叫salmon的鱼类的生命循环(life cycle)。(至于salmon是什么鱼,考生写作时完全可以不管!)循环型流程图的关键是辨明起点。在本图中,可借助已有①、②、③的标记,选择从最上面的“产卵”开始即可。图中将salmon的整个生命流程用了三个小图来说明,描写时可据此分为三个步骤来描述,每个步骤用两到三句即可。注意最下面的图介绍了salmon三个时期的名称和身长,这些信息应加入到各个步骤的描述中。
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