potato是不是可数名词?

　　例句

　　1、The potato cakes should be crisp outside and meltingly soft inside.

　　土豆饼应该外面酥脆,里面嫩软.

　　2、Now experts are extolling the virtues of the humble potato.

　　现在专家们都在赞美其貌不扬的`马铃薯的种种好处。

　　3、Left-handers have trouble using can-openers, scissors, and potato peelers.

　　左撇子在使用开罐刀、剪刀和土豆削皮器时会有困难。