In modern Chinese the conjunction "因為" (because, since, as, for, etc.) is assumed to read "yīnwèi", the character "為" namely reads the fourth-tone, and the tones of this word are marked in this wise in almost all Chinese dictionaries. The journal Yaowen Jiaozi also publishes an article to discuss this issue. According to the research, however, this word should be the abbreviation of the phrase "the reason is", the character "為" thus functions as the verb "be" and should read the second-tone "wéi". This article will bring this issue up for a renewed discussion.