Spectra lines of CO and HCO⁺ toward the eight sightlines. The upper panel for each plot shows ¹²CO emission lines (1 → 0) in black, obtained from the FUGIN survey (Umemoto et al. 2017), and ¹³CO (1 → 0) emission lines in red from the GRS survey (Jackson et al. 2006). For only G09.62+0.19, the ¹²CO (2 → 1) is taken from the SEDIGISM survey (Schuller et al. 2021). The lower panel for each plot shows absorption and emission lines in HCO⁺ spectra in blue from this survey. In the both panels, the vertical dotted lines indicate significant absorption features.