Once language starts to develop from about age 2, they do have a system for symbolic representation and can talk about things which aren't in their immediate environment including the past.
一旦语言从2岁左右开始发展，他们就有了一个符号表征系统，可以谈论过去和现在环境之外的事情。
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Because the interaction is based on a URI rather than an API, a client written in any language can receive a representation via an HTTP request.
Given a language, define a representation for its grammar along with an interpreter that USES the representation to interpret sentences in the language.