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The discovery of the ground state positive-parity charm-strange and charm-nonstrange mesons Ds0*$ D_{s0}^* $(2317), Ds1(2460), D0*$ D_0^* $(2400) and D1(2430) in 2003 and 2004 brought up several mysteries related to their masses. Here I briefly review recent progresses from lattice calculations and analysis of the precise LHCb measurements of the B−→ D+π−π− in the framework of unitarized chiral perturbation theory. It turns out that all the mysteries can be understood in a picture consistent with both lattice results and the LHCb measurements. In this picture, the main components of Ds0*$ D_{s0}^* $(2317) and Ds1(2460) are DK and D∗K hadronic molecules, respectively. Furthermore, the resonance parameters of the ground state 0+ and 1+ charm-nonstrange mesons take values very different from the known ones of the D0*$ D_0^* $(2400) and D1(2430), which were obtained by using an improper resonance parameterization. It is pointed out that there should be two D0*$ D_0^* $ and two D1 broad states in region relevant to the D0*$ D_0^* $ (2400) and D1(2430). Suggestions towards identifying the higher nonstrange resonances are given.