Xué / shēng / men / duì / zhè / ge / yǔ / fǎ / guī / zé / sì / dǒng / fēi / dǒng / xū / yào / lǎo / shī / zài / jiě / shì / yí / biàn

学生们对这个语法规则似懂非懂，需要老师再解释一遍。

The students only half understand this grammar rule and need the teacher to explain it again.