When do you think is necessary to tell a lie?

Generally speaking,it's wrong to tell a lie.Besides,there are many disadvantages lying in the way of a liar.
First,he has to have a good memory,because he is afraid that his liar may be found out.Second,a liar is never trusted and respected by others.The result may be that his words,even when he speaks the truth,are not believed.Third and the last,once a person has told a lie,he cannot help telling another in order to hide the first,and then a third and a fourth,until lying becomes a habit.After that,he may say something untrue even when he wishes to speak the truth.
So If you want to be a trustworthy person,never tell a lie.