tokens: We are grateful to Stephen Justham at National Astronomical Observatories, Chinese Academy of Sciences (CAS), for discussions. R.X.X. acknowledges the support of National Key RD Program of China (No. 2017YFA0402602), National Natural Science Foundation of China (NSFC) 11673002 and U1531243. W.Y.W. and X.L.C. acknowledge the support of MoST 2016YFE0100300, NSFC 11473044, 11633004, 11373030, CAS QYZDJ-SSW-SLH017. R.L. and K.J.L. are supported by NSFC U15311243 National Basic Research Program of China, 973 Program, 2015CB857101, XDB23010200, 11690024, 11373011, and funding from the Max-Planck Partner Group.
ner_tags: O O O O B-Person I-Person O B-Observatory I-Observatory I-Observatory B-Organization I-Organization I-Organization I-Organization B-Organization O O B-Person O O O O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant B-Grant I-Grant B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization B-Grant O B-Grant B-Person O B-Person O O O O B-Organization B-Grant B-Organization B-Grant B-Grant B-Grant B-Organization B-Grant B-Person O B-Person O O O B-Organization B-Grant B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant I-Grant I-Grant B-Grant B-Grant B-Grant B-Grant O O O O B-Organization I-Organization I-Organization