lǎo / shī / jiǎng / jiě / zhè / shǒu / cí / shí / xiān / shuō / míng / le / tā / suǒ / yòng / de / zhé / kǒu

老师讲解这首词时，先说明了它所用的辙口。

When explaining the poem, the teacher first described its rhyme category.