海龟的外貌特征: graceful,sleek 海龟的身体结构: flipper,shell, scute,lung, body, skin,head, limb海龟的行为动作: travel, swim,dig, breathe, cover, return,crawl,dine, munch,swallow 海龟的食物: plant,animal,alga,sea grass,crab,conch hold one's breath 屏住呼吸 for sure 无疑;肯定 byaccident 偶然地;意外地 in charge of...主管......; 负责·..... dine on... 正餐吃......; 以......作正餐 定语从句: They are one of the few reptiles that live in the sea. 形容词最高级的表达方式:lt's the world's most endangered seaturtle. 宾语从句: Scientists aren't sure how sea turtles know where to go.条件状语从句: If the hatchlings follow this light, they will make it tothe sea. 动名词短语作主语: Swallowing trash can hut and even kill seaturtles.