CH₃CCH spectra at the peak emission of clumps C, MM2, and MM3. For clump MM2, the CH₂CHCN emission is detected, with red line showing the fitting result. In all plots, whenever there are more than one velocity component, both the composite line profile of the fits (green line) and the individual fit for each component (blue lines) are shown. The parameters of the peak intensity (T_mb) and linewidth (∆V) are listed in Table 4.