Dependence of SFR (left panel) and SFE (right panel) on the clustercentric radius indicated by ﹩{k}_{b}=(| {\rm{\Delta }}v| /{\sigma }_{\mathrm{cluster}})\times (R/{R}_{200{\rm{c}}})﹩. The SFR of each galaxy is normalized by field MS galaxies, while the SFE is normalized by field galaxies at the same ΔMS (Magdis et al. 2012; Tacconi et al. 2018). Galaxies are color-coded by their gas fraction normalized by the field galaxies at the same ΔMS. A general trend of enhanced SFE toward the cluster center is revealed. The low gas fraction, yet normal or suppressed SFR of the member galaxies in the cluster center, suggests that their enhanced SFE is mainly caused by their deficit of molecular gas (instead of an enhanced SFR).