CREATE TABLE Teachers (address_id VARCHAR2)
CREATE TABLE Students (address_id VARCHAR2)
CREATE TABLE Addresses (line_1 VARCHAR2, address_id VARCHAR2)

What are the line 1 of addresses shared by some students and some teachers?
SELECT T1.line_1 FROM Addresses AS T1 JOIN Students AS T2 ON T1.address_id = T2.address_id INTERSECT SELECT T1.line_1 FROM Addresses AS T1 JOIN Teachers AS T2 ON T1.address_id = T2.address_id
SELECT "T1"."line_1" FROM "Addresses" "T1" JOIN "Students" "T2" ON "T1"."address_id" = "T2"."address_id" INTERSECT SELECT "T1"."line_1" FROM "Addresses" "T1" JOIN "Teachers" "T2" ON "T1"."address_id" = "T2"."address_id"