现代语言学研究语言体系、言语活动、言语机制和话语等方面,各方面是相互循环的。内循环是语言体系、言语活动、言语机制和话语之间的相互循环,外循环是语言体系和文字体系之间、主管言语机制的人脑和进行语言信息处理的电脑之间的循环。各项循环构成一个相互联系、相辅相成的建构性的循环网络。语言学的这一发展趋势为外语教学提供了理论基础。 Modern linguistics studies various aspects of the language system, speech activities, speech mechanisms and discourses. The inner circle is the cycle of language system, speech activity, speech mechanism and discourse. The outer cycle is the cycle between the language system and the writing system, between the human brain in charge of speech mechanism and the computer in which language information is processed. The cycles form an interlinked and complementary network of constructive cycles. This trend of linguistics provides a theoretical basis for foreign language teaching.