correct dependency tree formatting

Book/Chapter2/Figures/figure-phrase-structure-tree-and-dependency-tree.tex

@@ -70,9 +70,9 @@
 \node [anchor=west,inner sep=2pt] (w3) at ([xshift=4.5em]w1.east) {吃};
 \node [anchor=west,inner sep=2pt] (w4) at ([xshift=2em,yshift=-3em]w3.east) {鱼};
 
-\draw [<-,ultra thick,ublue] (w1.north east) -- (w2.south) node [pos=0.3, above, xshift=-0.5em] {\color{red}{\tiny{主谓}}};
-\draw [<-,ultra thick,red] (w3.north west) -- (w2.south) node [pos=0.3, above, xshift=0.5em] {\color{red}{\tiny{连动}}};
-\draw [->,ultra thick,ugreen] (w3.south east) -- (w4.north west) node [pos=0.5, above, xshift=0.5em] {\color{red}{\tiny{谓宾}}};
+\draw [-,ultra thick,ublue] (w1.north east) -- (w2.south) node [pos=0.3, above, xshift=-0.5em] {\color{red}{\tiny{主谓}}};
+\draw [-,ultra thick,red] (w3.north west) -- (w2.south) node [pos=0.3, above, xshift=0.5em] {\color{red}{\tiny{连动}}};
+\draw [-,ultra thick,ugreen] (w3.south east) -- (w4.north west) node [pos=0.5, above, xshift=0.5em] {\color{red}{\tiny{谓宾}}};
 
 \end{scope}