It seems there is no solution for inserting a vector-based figure (e.g. PDF) into MS Office (Word and Powerpoint). Someone suggest to convert into a high-resolution image first, e.g. this oneand this one. However, none of the workarounds will keep the insertion as a vector-based figure (which has many advantages than raster-based figure, e.g. you can select and search). My workaround is, save the powerpoint as PDF after insertion. In that way, you can keep the insertion in vector-based figure. Anyone knows better solution?