National Astronomical Observatories;
Chinese Academy of Sciences;
Beijing 100101;
China;
Shanghai Astronomical Observatory;
Chinese Academy of Sciences;
Shanghai 200030;
China;
Kavli Institute for Astronomy and Astrophysics;
Peking University;
Beijing 100871;
China;
School of Physics and Astronomy;
Shanghai Jiao Tong University;
800 Dongchuan Road;
Shanghai 200240;
China;
cosmology:observations; dark ages; reionization; radio lines:general; methods:observational;