今天几号?Jīntiān jǐ hào? What's the date today? 今天12号。Jīntiān 12 hào. Today is the 12th.
明天几号?Míngtiān jǐ hào? What's the date tomorrow? 明天13号。Míngtiān 13 hào.
Tomorrow is the 13th.
昨天几号?Zuótiān jǐ hào? What's the date yesterday? 昨天11号。 Zuótiān 11 hào.
Yesterday was the 11th.