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/ˈpleɪsˌhəʊldə(r)/noun
1
- Mathematics a significant zero in the decimal representation of a number【数】有效零。
1.1
- 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。
2
- 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, 形式主语, 形式宾语（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）。