Context: CREATE TABLE Courses (author_id VARCHAR, course_name VARCHAR); CREATE TABLE Course_Authors_and_Tutors (address_line_1 VARCHAR, author_id VARCHAR)
Question: Find the addresses of the course authors who teach the course with name "operating system" or "data structure".
Answer: SELECT T1.address_line_1 FROM Course_Authors_and_Tutors AS T1 JOIN Courses AS T2 ON T1.author_id = T2.author_id WHERE T2.course_name = "operating system" OR T2.course_name = "data structure"