一字之師

one who can correct a misread or misspelt character and thus be your master

one / single / a (article) / as soon as / entire; whole; all; throughout / "one" radical in Chinese characters (Kangxi radical 1) / also pr. [yao1] for greater clarity when spelling out numbers digit by digit

in a row / in a line

letter / symbol / character / word / CL:個|个[ge4] / courtesy or style name traditionally given to males aged 20 in dynastic China

(possessive particle, literary equivalent of 的[de5]) / him / her / it

surname Shi

teacher / master / expert / model / army division / (old) troops / to dispatch troops