pen是可數名詞還是不可數名詞

　　Go and get me a pen please.

　　請你去給我拿支鋼筆來。

　　I could hear his pen scraping across the paper.

　　我聽得見他的鋼筆在紙上沙沙地響。

　　At the stroke of a pen they removed thousands of people from the welfare system.

　　他們大筆一揮，就把成千上萬的人排除在福利制度之外。

　　None of these pens works/ work.

　　這些鋼筆沒有一支能用。

　　She reached inside her bag for a pen.

　　她把手伸到包里掏鋼筆。