Welcome back, Farsi detectives, we have another mystery to solve! This one is called the نشانه ـُ استثنا (the ‘o’ vowel exception). In this case, you see a word written with the letter Vav (و), which you think should make the ‘u’ sound. But—plot twist!—it magically makes the short ‘o’ sound instead. This happens in very common words like the Farsi word for “you,” تو (to), and “two,” دو (do).