zài / shēng wù kè / shàng / lǎo shi / jiǎng jiě / le / bàn sāi gāng / de / zhǔ yào / tè zhēng

在生物课上，老师讲解了瓣鳃纲的主要特征。

In biology class, the teacher explained the main characteristics of Lamellibranchia.