先体验一下A1版

Release candidate[edit]
A release candidate (RC) is a beta version with potential to be a final product, which is ready to release unless significant bugs emerge. In this stage of product stabilization, all product features have been designed, coded and tested through one or more beta cycles with no known showstopper-class bug. A release is called code complete when the development team agrees that no entirely new source code will be added to this release. There could still be source code changes to fix defects, changes to documentation and data files, and peripheral code for test cases or utilities. Beta testers, if privately selected, will often be credited for using the release candidate as though it were a finished product. Beta testing is conducted in a client's or customer's location and to test the software from a user's perspective.
摘自wikipedia

rc 是 release candidate，可以算是成为最终产品的候选人，除非有严重的bug出现。rc1应该不是首位，因为好像还有个rc2还没有上传，估计是根据alpha2改良的。

不管了，先装个试一试！