zài / wēi / fēn / jǐ / hé / kè / shàng / lǎo / shī / jiè / shào / le / liú / xíng / de / jī / běn / gài / niàn在微分几何课上,老师介绍了流形的基本概念。In the differential geometry class, the teacher introduced the basic concept of manifolds.