Dust continuum images of disks with multiple rings in our sample and the literature. Most of the multiple-ring systems are centrally filled (F-type) (Andrews et al. 2018a; Cieza et al. 2021; Ohashi et al. 2023; Hsieh et al. 2024; Cieza et al. 2019; ALMA Partnership 2015; Stephens et al. 2023). The lack of a large central cavity (≥25% of the disk diameter) implies that a centrally filled disk is a general feature of multiple-ring systems. The cyan circle represents the beam size. The white lines mark the scale of 50 au. Note that HD 163296, RU Lup, AS 209, GW Lup, HD 142666, HD 143006, and Sz 129 either do not have reliable bolometric temperature (T_bol) measurements or their T_bol ≥ 1900 K, thus are not included in this study.