试题题干
According to the records available, human beings have been involved in the study of language for （ ） years.
参考答案
正确答案：
试题解析
根据现有记录，人类已经参与了2500年的语言研究。
According to the records available, human beings have been involved in the study of language for （ ） years.
根据现有记录，人类已经参与了2500年的语言研究。