lǎo / shī / zài / hēi / bǎn / shàng / xiě / le / yí / gè / sú / tǐ / zì / tí / xǐng / wǒ / men / bú / yào / bǎ / tā / yòng / zài / zuò / wén / lǐ

老师在黑板上写了一个俗体字，提醒我们不要把它用在作文里。

The teacher wrote a nonstandard character on the blackboard and reminded us not to use it in our essays.