tīng / le / lǎo / shī / de / jiě / shì / tā / dùn / shí / kāi / le / xīn / qiào / míng / bai / le / wèn / tí / de / guān / jiàn

听了老师的解释，她顿时开了心窍，明白了问题的关键。

After hearing the teacher's explanation, she suddenly understood and grasped the key point.