额...tough question...我自己用的时候是1以上用复数,1以下(包括decimal和fraction)用单数(这是以前老师教的...),但是平时看文章发现decimal用复数的也有。但有时候还是要看具体用法,查了下夸克语法大全,里面说到:
表示长度的foot与表示重量的pound常用零复数(单复数同型),尤其在它们之后接一个数词时(以下三者都对):
She's only five foot two. (这个时候要用foot)
She's only five foot/feet tall.
She's only five feet.(通常用法)
还有LDOCE里面的用法:
He's six feet tall , with blonde hair.
Mark was standing just a few feet away from me.(有人说"表示distance要用feet",点此链接到该网页)
I'd say she's about five foot three (=five feet and three inches) .