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.

         Cóng shàng dàxué de shíhòu yǐ lái, wǒ yì tiān jiǎ yě méiyǒu qǐng guò.
False: 从上大学的时候以来,我一天假也没有请过。
         Cóng shàng dàxué yǐ lái, wǒ yì tiān jiǎ yě méiyǒu qǐng guò./Shàng dàxué de shíhòu , wǒ yì tiān jiǎ yě méiyǒu qǐng guò.
True: 上大学以来,我一天假也没有请过。/上大学的时候,我一天假也没有请过。

两种表示时间的格式“……的时候”和“……以来”相互杂糅,只能取其中的一种说法。
……的时候 and ……以来 can not occur simultaneously. A choice has to be made between the two patterns.