1、Crustacea are a group of arthropods that typically have a hard exoskeleton and jointed appendages.
甲壳纲动物是一类通常具有硬外骨骼和关节附属肢的节肢动物。

2、Lobsters, crabs, and shrimp are all examples of crustacea.
龙虾、螃蟹和虾都是甲壳纲动物的例子。