Is it ethical to tell lies of the sort?

Many people, perhaps a majority, approve of telling lies to employers, co-workers, customers, or clients. Is it ethical to tell lies of the sort?  Begin by considering the following situations: (a) a doctor tells a patient he has consulted with a colleague about her condition, though no such consultation occurred; (b) a business executive tells a client that she was tied up in traffic when she really lingered over lunch with friends; (c) a composition teacher tells a student he is making progress in his writing when, in fact, the student is showing no progress.  Next, think of serval situations you are familiar with in which lies were told in the workplace.  Then explain in what circumstances, if any, lying is justifiable.