Examine the structure of the EMPLOYEES table:<br /> EMPLOYEE_ID NUMBER Primary Key<br /> FIRST_NAME VARCHAR2(25)<br /> LAST_NAME VARCHAR2(25)<br /> Which three statements inserts 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','NULL');

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',");