Is a whale mammal(哺乳动物）or a fish

Is a whale mammal(哺乳动物）or a fish As is known to all,the whale is not fish but a mammal.这句话中为什么fish前面不加a而mammal前面要加a呢? Is a whale a mammal or a fish?What is the meaninIs a whale a mammal or a fish?What is the meaning of “twenty-four seven”?These snacks are his.（用Tom改为选择疑问句）_____ these snacks ______ ____________? ln size,a sperm whale is()than a killer whale.a killer whale is()than a sperm whale the biggest whale is the blue whale.或the biggest whale is a blue whale.那个表达正确? How was the gap between a walking mammal and a swimming whale bridged?请问bridged什么意思?How was the gap between a walking mammal and a swimming whale bridged?Missing until recently were fossils clearly intermediate,or transitional,between lan Is a killer whale heavier than a sperm whale否定回答 A killer whale is ()than a sperm whale in its size啥意思 A sperm whale is ( )than a killer whale in its length啥意思 A killer whale is smaller than a sperm whale in its size.翻译 同义句 This kind is called a killer whale.We ( )this kind a killer whale.急 英语翻译翻译这句话A sperm whale is longer than a killer whale in its length. Is a whale a mamal or a fish? a whale is more an animal than a fish.翻译 The biggest whale is( )blue wale.A.the B.a 帮理解一个句子的语法：Miss until recently were...How was the gap between a walking mammal and a swimming whale bridged?Missing until recently were fossils clearly intermediate,or transitional,between land mammals and cetaceans.第二句是 Which is smaller,a blue whale or an elephant? A big sperm whale is about 16 meters ______.