Foreigners often make some strange mistakes in Chinese when they study the most difficult language--- ---Chinese. We try to analyze typical sentences to correct these errors.

          Mínɡtiān wǒmen chūfā xuéxiào.
False: 明天我们出发学校。
          Mínɡtiān wǒmen cónɡ xuéxiào chūfā.
True: 明天我们学校出发

出发 is a verb which does not take the object. To demonstrate the place of departure, one ought to use 从—— a preposition showing a space-time relationship. 从 plus its object 学校 forms a prepositional phrase, preceding 出发 as an adverbial adjunct.