张老师在设置教学目标时，既考虑学生的现有知识水平，也考虑他们在老师指导下可以达到的水平。维果斯基将这两种水平之间的差距称为（ ）。

(单选题)53.（ ） (单选题)52.（ ） (单选题)51.（ ） (单选题)Phonetics is the study of ______. (单选题)Which of the following is not one of the four maxims of the (单选题)Sometimes, two varieties of a language exist side by side th (单选题)Classification of English speech sounds in terms of manner o (单选题)Captain, My Captain is written for ______. (单选题)______ are not a minimal pair in English. (单选题)The only black woman writer awarded Nobel Prize of Literatur