电气设备的接地按其作用分为几种？

ALTER TABLE student_grades ADD FOREIGN KEY (student_id) REFERENCES students (student_id);
B. ALTER TABLE student_grades ADD CONSTRAINT NAME = student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);
C. ALTER TABLE student_grades ADD CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);
D. ALTER TABLE student grades ADD NAMED CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);
E. ALTER TABLE student grades ADD NAME student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id)

A. 专项顾问
B. 高端顾问
C. 综合性顾问
D. 基础顾问

A. “叙述”
B. “直述”
C. “论述”
D. “概述”
E. “转述&rdquo

A. 狄尔泰
B. 加分古尔
C. 舒茨