Ruby download is normal, installation is normal, gem test is normal.

Because gem foreign Yu’ an source is not useful, I intend to change the source. it is stuck in this step. ① the source can be deleted, but it cannot be added. ② the gemrc file can be searched directly. the source is active but cannot be used

(3) manually can add, but also can’t use

Several sources were changed, but none of them worked.