Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements insert a row into the table? （）

• A、INSERT INTO employees VALUES (NULL, 'John', 'smith');
• B、INSERT INTO employees (first_name, last_name) VALUES ('John', 'smith');
• C、INSERT INTO employees VALUES ('1000, 'John', 'smith');
• D、INSERT INTO employees (first_name, last_name, employee_id) VALUES (1000, 'John', 'smith');
• E、INSERT INTO employees (employee_id) VALUES (1000);
• F、INSERT INTO employees ( employee_id, first_name, last_name, ) VALUES (1000, 'John','');