单词：identifiers
n. 标示符；标识符；识别码（identifier的复数）
n a symbol that establishes the identity of the one bearing it
identifiers的用法和样例：
例句
用作名词(n.)
- Reserved words cannot be used as identifiers.保留字不能作为标识符使用。
- Which declarations of identifiers are legal?下面哪些是合法的标识符。