1. A sorus is a cluster of sporangia on the underside of fern fronds.
孢子囊群是蕨类叶片的背面上的一簇孢子囊。

2. The lecturer stood confidently at the sorus, ready to start his presentation.
讲师自信地站在讲台上，准备开始他的演讲。

3. The sorus on the fern leaf looked like a delicate feather.
蕨叶上的孢子囊群看起来像一片精致的羽毛。