您是否先运行brew update?如果您不这样做，Homebrew将无法更新其公式，并且如果不更新其公式，那么它将不知道如何安装最新版本的软件.

Have you run brew update first? If you don't do that, Homebrew can't update its formulas, and if it doesn't update its formulas it doesn't know how to install the latest versions of software.