\node[sentence] (node1) at (0,0) {[`low', `lower', `newest', `widest']};
\node[sentence] (node1) at (0,0) {['low', 'lower', 'newest', 'widest']};
\node[sentence,anchor = north] (node2) at ([yshift = -1em]node1.south) {[`l o w $<$e$>$':5, `l o w e r $<$e$>$':2, `n e w e s t $<$e$>$':6, `w i d e s t $<$e$>$':3]};
\node[sentence,anchor = north] (node2) at ([yshift = -1em]node1.south) {['l o w $<$e$>$':5, 'l o w e r $<$e$>$':2, 'n e w e s t $<$e$>$':6, 'w i d e s t $<$e$>$':3]};
\node[sentence,anchor = north] (node3) at ([yshift = -1.5em]node2.south) {[`l o w $<$e$>$':5, `l o w e r $<$e$>$':2, `n e w {\red es} t $<$e$>$':6, `w i d {\red es} t $<$e$>$':3]};
\node[sentence,anchor = north] (node3) at ([yshift = -1.5em]node2.south) {['l o w $<$e$>$':5, 'l o w e r $<$e$>$':2, 'n e w {\red es} t $<$e$>$':6, 'w i d {\red es} t $<$e$>$':3]};
\node[sentence,anchor = north] (node4) at ([yshift = -1em]node3.south) {[`l o w $<$e$>$':5, `l o w e r $<$e$>$':2, `n e w {\red est}$<$e$>$':6, `w i d {\red est}$<$e$>$':3]};
\node[sentence,anchor = north] (node4) at ([yshift = -1em]node3.south) {['l o w $<$e$>$':5, 'l o w e r $<$e$>$':2, 'n e w {\red est}$<$e$>$':6, 'w i d {\red est}$<$e$>$':3]};
\node[sentence,anchor = north] (node5) at ([yshift = -1em]node4.south) {[`l o w $<$e$>$':5, `l o w e r $<$e$>$':2, `n e w {\red est$<$e$>$}':6, `w i d {\red est$<$e$>$}':3]};
\node[sentence,anchor = north] (node5) at ([yshift = -1em]node4.south) {['l o w $<$e$>$':5, 'l o w e r $<$e$>$':2, 'n e w {\red est$<$e$>$}':6, 'w i d {\red est$<$e$>$}':3]};
\node[sentence,anchor = north] (node6) at ([yshift = -1em]node5.south) {$\cdots$};
\node[sentence,anchor = north] (node6) at ([yshift = -1em]node5.south) {$\cdots$};
\node[node,anchor = north] (node7) at ([yshift = -1.6em]node6.south) {直到达到预设的子词词表大小或下一个最高频的字节对出现频率为1。};
\node[node,anchor = north] (node7) at ([yshift = -1.6em]node6.south) {直到达到预设的子词词表大小或下一个最高频的字节对出现频率为1。};