bird是可數名詞還是不可數名詞?

　　The bird disappeared into the scrub.

　　鳥消失在矮樹叢中。

　　The bird flapped its wings furiously.

　　那只鳥使勁地拍打著翅膀。

　　There was a bird perched on the roof.

　　有一只鳥落在屋頂上。

　　A bird had pecked a hole in the sack.

　　一只鳥把袋子啄了個洞。

　　The bird fanned out its tail feathers.

　　這只鳥把尾羽展成扇形。

　　The bird caught the insects in mid-air.

　　鳥在半空中捕捉了昆蟲。