9. As shown in Figure a, 7 Chinese characters are written in the 7 circles in the figure, requiring to start from a certain circle and draw the figure in one stroke (all circles must be visited, and each can only be visited once), forming a string of characters along the path of this one-stroke drawing (as shown in Figure b, starting from “中” to draw in one stroke, the resulting string is “中环难杯真的好”). Therefore, the number of different strings that can be formed is $\qquad$.


【Analysis】Starting from 中, the substrings formed are:
From 中 to 难, there are 2: 中难环杯真的好, 中难好的真杯环
From 中 to 环, there are 8: 中环难杯真的好, 中环难好的真杯, 中环杯难真的好, 中环杯难好的真, 中环杯真难好的, 中环杯真难的好, 中环杯真的难好, 中环杯真的好难
Therefore, from 中 to 好, there are also 8
Thus, the routes starting from 中 total 18
Therefore, the routes starting from 环, 杯, 真, 的, 好, 难 also total 18
Starting from 难, the first step has 6 choices, followed by 2 choices of clockwise or counterclockwise, so the substrings starting from 难 have
12
In summary, there are $18 \times 6+12=120$ different substrings