線是可數名詞還是不可數名詞

　　It took me a long time to thread my way through the crowd.

　　我花了很長時間才從人群中擠過去。

　　The author skilfully draws together the different threads of the plot.

　　作者嫻熟地把情節的各種線索串聯在一起。

　　A common thread runs through these discussions.

　　這些討論都貫穿著一條共同的主線。

　　A tiny wire is threaded through a vein to the heart.

　　一根細金屬絲從靜脈里穿到心臟。

　　She snipped at the loose threads hanging down.

　　她把垂下來的線頭剪掉。