名词
中文翻译：背鳍
同义词：
['dorsal fin', 'pectoral fins例句：1. The fish swims with its back fin sticking out of the water.（这条鱼游动时，它的背鳍从水中露出来。）2. The dolphin has a unique ability to use its pectoral fins to propel itself through the water.（海豚有一种特殊的能力，能够使用胸鳍在水中推进自己。）']
例句：
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1. The fish swims with its back fin sticking out of the water.
这条鱼游动时，它的背鳍从水中露出来。
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2. The dolphin has a unique ability to use its pectoral fins to propel itself through the water.
海豚有一种特殊的能力，能够使用胸鳍在水中推进自己。
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3. In some species of shark, the pectoral fins are modified into powerful tails for swimming.
在鲨鱼的某些种类中，胸鳍被改造成有力的尾巴用于游泳。