第 1 题 · 四级
The keeper feeds the animals every morning, which keeps them healthy.
核心词：keeper ˈkiːpə n. 饲养员；看守人
饲养员每天早晨喂动物，这使它们保持健康。
一般现在时主谓宾 + which 非限制性定语从句短语 a keeper短语 keep healthy
The ___ feeds the animals every morning, which keeps them healthy.
第 2 题 · 四级
The ship was sailing across the sea when the storm suddenly came.
核心词：sail seɪl v. 航行；n. 帆
风暴突然来临时，船正在海上航行。
过去进行时过去进行时 + when 时间状语从句短语 sail across短语 set sail
The ship was ___ across the sea when the storm suddenly came.
第 3 题 · 四级
The shell of the egg was broken, which the cook used for a cake.
核心词：shell ʃel n. 壳，贝壳
蛋壳破了，厨师用它做蛋糕。
一般过去时一般过去被动 + which 定语从句短语 a shell短语 be broken
The ___ of the egg was broken, which the cook used for a cake.
