Complete the following sentence with a (compound) word derived f

Complete the following sentence with a (compound) word derived from the one(s) given in bracket.

A （ ） is not believed when he speaks the truth.(lie)

根据前文a，后文is，说明空格处应该填主语，词性为名词，lie的名词形式为liar说谎的人，且符合句意。句意：经常说谎的人说真话是不会被相信的。