lǎo / shī / yòng / tú / biǎo / bāng / zhù / xué / shēng / qū / fēn / dān / mǔ / yīn / hé / fù / hé / mǔ / yīn老师用图表帮助学生区分单母音和复合母音。The teacher used a chart to help students distinguish monophthongs from diphthongs.