chū mén qián / tā / fā xiàn / shǒu wàn shàng / de / tóu shéng / bú jiàn le / zhǐ hǎo / qǐng / tóng xué / jiè gěi / tā / yì gēn

出门前，她发现手腕上的头绳不见了，只好请同学借给她一根。

Before leaving, she discovered that the hair tie around her wrist was gone, so she had to ask a classmate to lend her one.