(Mathematics)a significant zero in the decimal representation of a number (数)有效零 ■a symbol or piece of text used in a mathematical expression or in an instruction in a computer program to denote a missing quantity or operator 占位符号
(Linguistics)an element of a sentence that is required by syntactic constraints but carries little or no semantic information, for example the word it as a subject in it is a pity that she left, where the true subject is that she left (语言学)占位成分(句法规则要求,但又没有语义信息的句子成分,例如: it is a pity that she left一句中的主语it,that she left才是真正的主语)