Which statement fails to execute successfully?

Which three actions can you perform by using the ALTER TABLE command?

Which three statements are true about the DESCRIBE command?

Examine this query:
SELECT SUBSTR (SYSDATE,1,5) 'Result' FROM DUAL
Which statement is true?

Examine these two queries and their output:
SELECT deptno, dname FROM dept;

SELECT ename, job, deptno FROM emp ORDER BY deptno;

Now examine this query:
SELECT ename, dname
FROM emp CROSS JOIN dept WHERE job = 'MANAGER'
AND dept.deptno IN (10, 20) ;