听力原文:W: I hear you're going to drive to Shanghai this weekend. M: Oh, I've changed my mind. W: What? M: I think flying will be more comfortable. How will the man get to Shanghai?
【简答题】18-59 The Wittig reaction is useful for placing double bonds in less stable positions. For example, the following transformation is easily accomplished using a Wittig reaction. (a) Show how you w...