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: 从上大学以来，我一天假也没有请过。/上大学的时候，我一天假也没有请过。