shí / yàn / shí / xué / shēng / zài / lǎo / shī / zhǐ / dǎo / xià / xiǎo / xīn / pèi / zhì / qīng / yǎng / huà / jiǎ / róng / yè

实验时，学生在老师指导下小心配制氢氧化钾溶液。

During the experiment, the students carefully prepared a potassium hydroxide solution under the teacher's guidance.