Molecule-dependent abundance behavior of oxygen-bearing complex organics in high-mass star-forming regions: A uniform 50-source survey

We present a uniform IRAM-30,m survey analysis of four oxygen-bearing complex organic molecules (COMs) -- methanol (CH_3OH), acetaldehyde (CH_3CHO), methyl formate (CH_3OCHO), and dimethyl ether (CH_3OCH_3) -- toward 50 high-mass star-forming regions (HMSFRs) associated with 6.7,GHz methanol masers. Column densities were derived through a homogeneous rotation-diagram approach, with CH_3CN used as a proxy excitation-temperature reference when needed. In the CH_3OH-normalized abundance-ratio space, CH_3OCHO/CH_3OH and CH_3OCH_3/CH_3OH show the strongest pairwise correlation, whereas the correlations involving CH_3CHO are weaker. No clear monotonic trends are found with galactocentric distance or beam-averaged H_2 column density. Comparison with previous observations places the CH_3OCHO--CH_3OCH_3 behavior within the range of earlier abundance-ratio measurements, while CH_3CHO shows larger inter-study variation. A representative warm-up chemical model was used only for qualitative comparison with the observed abundance ranges, which are most closely matched during the decline from the post-desorption abundance peaks in the model. These results provide homogeneous beam-averaged abundance-ratio constraints for common O-bearing COMs in HMSFRs and show that their source-to-source behavior is molecule-dependent rather than fully described by a single common abundance pattern.