wù / lǐ / kè / shàng / lǎo / shī / qiāo / jī / yīn / chā / yǎn / shì / shēng / yīn / de / zhèn / dòng物理课上,老师敲击音叉演示声音的振动。In physics class, the teacher struck a tuning fork to demonstrate sound vibration.