\begin{document}
\begin{tikzpicture}[scale=2, line width=1.5pt,
every node/.style={draw=black, circle, very thick,font =\huge, minimum size=3em},
arrow/.style={-latex, red}
]
% 使用箭头连接节点,并在箭头之间创建节点
\draw[arrow,shorten >=1.5em, shorten <=1.5em] (0,0) node (A) {A} -- (2,0) node (B) {B} -- (4,0) node (C) {C};
%\draw[arrow, shorten >=1ex] (0,0) -- (2,-2) node (D) {D};
%\draw[arrow] (C) -- (D);
\end{tikzpicture}
\end{document}