<綜合測驗>第16至20題為題組 The art and tradition of using all-natural paste from the henna plant to create temporary henna tattoos goes back to ancient Asia and the Middle East. Over the centuries， henna tattoos ___16___ used in weddings and holiday celebrations because they are thought to carry blessings from the gods. (A) were being (B) have been (C) will be (D) had to be
