Spectra of [S II] auroral lines (top left), [O II] auroral lines (top right), [S III] auroral line (mid left), [O III] auroral line (mid right), and [N II] auroral line (bottom left) from a sample bin $({\mathrm{Z}}_{-0.15}^{-0.10},\log (\mathrm{U}{)}_{-2.85}^{-2.80})$ with 2909 spaxels. In each panel, from top to bottom, the three rows correspond to a single spectrum, the stacked spectrum (blue), as well as the best-fit stellar continuum spectrum(red), and the stacked spectrum after removing the stellar continuum, where the auroral lines can be clearly detected. The shaded regions of the top row represent the uncertainties of flux, taken from MaNGA maps files. The shaded regions of the stacked spectra are errors propagated from individual spaxels. In the [O III] panel, the dashed gray lines represent the [Fe II]λ 4359 (right) and [Fe II] λ 4288 (left).