During the class,our teacher used to expanding/introuducing lots of new knowledge surrounding this sentence
注：1.used to doing sth是指習慣于干某事,常常怎么樣；
2.要是前后文中提到一句話的話用this或者the sentence,如果沒有特別說明那句話最好將this換成 a,表示泛指
3.個人覺得用introuduce更好一點,因為老師講課更多的就是引入知識,用expand的話感覺太生硬了,還有如果這位老師可以直接說出名字的話,可以直接把our teacher換成Mr./Miss./Mrs./Dr.+姓,會比較親切.
再就是可以說的簡單點：
While having classes,our teacher often introuduces some new information surrounding a sentence.