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口头证据 means:
名词
neolog
noun
Under Chinese law, there is no such concept as "parol evidence" which prevents prior discussions or oral agreements from being admitted as evidence. In fact, ancillary evidence such as prior negotiations can be used to help contractual interpretation.
any matters discussed, either orally or in writing, during the drafting of a legal document (eg a contract) that are not included in the final written document
The judge ruled that he would not consider any parol evidence regarding the alleged term.