bird是可數(shù)名詞還是不可數(shù)

　　例句：

　　This species of bird is decreasing in numbers every year.

　　這種鳥的數(shù)量在逐年減少。

　　The area has a wealth of bird life.

　　這個(gè)地區(qū)棲息著大量的鳥。

　　The lake is noted as a home to many birds.

　　這個(gè)湖作為許多鳥類的棲息地而聞名。

　　Ten new cases of bird flu were reported yesterday.

　　昨天新增十例禽流感病例報(bào)告。