\begin{tikzpicture}

\begin{scope}
\node [anchor=north west] (pos1) at (0,0) {$\circ$};
\node [anchor= west] (pos2) at ([xshift=3.0em]pos1.east){$\circ$};
\node [anchor= west] (pos1-2) at ([xshift=1.0em,yshift=1.0em]pos1.east){I};
\draw[->,thick](pos1.east)--(pos2.west);
\node [anchor= west] (pos3) at ([xshift=3.0em]pos2.east){$\circ$};
\node [anchor= west] (pos2-2) at ([xshift=0.1em,yshift=1.0em]pos2.east){have};
\draw[->,thick](pos2.east)--(pos3.west);

\end{scope}

\begin{scope}[yshift=-4.0em]
\node [anchor=north west] (pos1) at (0,0) {$\circ$};
\node [anchor= west] (pos2) at ([xshift=3.0em]pos1.east){$\circ$};
\node [anchor= west] (pos1-2) at ([xshift=0.5em,yshift=1.0em]pos1.east){He};
\draw[->,thick](pos1.east)--(pos2.west);
\node [anchor= west] (pos3) at ([xshift=3.0em]pos2.east){$\circ$};
\node [anchor= west] (pos2-2) at ([xshift=0.1em,yshift=1.0em]pos2.east){has};
\draw[->,thick](pos2.east)--(pos3.west);
\node [anchor= west] (pos4) at ([xshift=5.0em]pos3.east){$\circ$};
\node [anchor= west] (pos5) at ([xshift=5.0em]pos4.east){$\circ$};
\node [anchor= west] (pos6) at ([xshift=5.0em]pos5.east){$\circ$};

\node [anchor= west] (word1) at ([xshift=2.0em,yshift=2.7em]pos4.east){I};
\node [anchor= west] (word2) at ([xshift=1.5em,yshift=-1.6em]pos4.east){He};
\node [anchor= west] (word3) at ([xshift=1.4em,yshift=-3em]pos4.east){She};
\node [anchor= west] (word4) at ([xshift=1.1em,yshift=2.8em]pos5.east){Have};
\node [anchor= west] (word5) at ([xshift=1.3em,yshift=-2.8em]pos5.east){Has};
\node [anchor= south] (labelb) at ([xshift=3em,yshift=-3em]word3.south){\small{(b)Lattice词串表示}};
\begin{pgfonlayer}{background}
{
% I
\draw [->,thick] (pos4.north) .. controls +(north:0.8) and +(north:0.8) .. (pos5.north);
% He
\draw [->,thick] (pos4.south) .. controls +(south:0.8) and +(south:0.8) .. (pos5.south);
% She
\draw [->,thick] (pos4.south) .. controls +(south:1.5) and +(south:1.5) .. (pos5.south);

% Have
\draw [->,thick] (pos5.north) .. controls +(north:0.8) and +(north:0.8) .. (pos6.north);
% Has
\draw [->,thick] (pos5.south) .. controls +(south:0.8) and +(south:0.8) .. (pos6.south);
}
\end{pgfonlayer}

\end{scope}

\begin{scope}[yshift=-8.0em]
\node [anchor=north west] (pos1) at (0,0) {$\circ$};
\node [anchor= west] (pos2) at ([xshift=3.0em]pos1.east){$\circ$};
\node [anchor= west] (pos1-2) at ([xshift=0.4em,yshift=1.0em]pos1.east){She};
\draw[->,thick](pos1.east)--(pos2.west);
\node [anchor= west] (pos3) at ([xshift=3.0em]pos2.east){$\circ$};
\node [anchor= west] (pos2-2) at ([xshift=0.1em,yshift=1.0em]pos2.east){has};
\draw[->,thick](pos2.east)--(pos3.west);
\node [anchor= south] (labela) at ([xshift=2em,yshift=-3em]pos1-2.south){\small{(a)$n$-best词串表示}};
\end{scope}

\end{tikzpicture}
%---------------------------------------------------------------------