原来如此

Explanation: Said that the original truth. So it is. 　　Source: Qing Cao Xueqin's "Dream of Red Mansions," the sixty-sixth back to the original case, down to teach us a few days hanging heart. " Thesaurus:  achieve mastery through a comprehensive study of the subject, draw inferences about other cases from one instance, suddenly see the light, tumble, be suddenly enlightened, Suddenly transfixion, Small clues tell, Gammer Nengjie, Corner of the three anti-, To know the micro-, sudden show of wit, understanding, etc （ Antonym Group:  Xi Yan Review, Learning rather than the police, Dream such as drunk, be imbeded in, s Dream Day, Trance, Gutengroufei, Hunqianmengying