documentclass{beamer}
mode<presentation> {
setbeamercovered{transparent}
useoutertheme{infolines}
usetheme{CambridgeUS}
usecolortheme{dolphin}
}
newtheorem{lema}{Lemma}[section]
begin{document}
begin{frame}
Suppose
\begin{lema}\label{le3}
Suppose
\end{lema}
end{frame}
end{document}
`
问 lemma 环境内和lemma外面的字体不一样