Zhǐ / duǎn / qíng / cháng / zhè / fēng / xìn / xiě / bu / jìn / wǒ / duì / nǐ / de / sī / niàn

纸短情长，这封信写不尽我对你的思念。

The letter is too short for my feelings; it cannot express how much I miss you.