第 1 题 · 高考
Hydrogen is a light gas, which is used to fill balloons.
核心词：hydrogen ˈhaɪdrədʒən n. 氢
氢是一种轻气体，用来给气球充气。
被动语态 + which 定语从句短语 hydrogen短语 hydrogen energy
___ is a light gas, which is used to fill balloons.
第 2 题 · 高考
They went on a long hike in the mountains, which took them the whole day.
核心词：hike haɪk n. 徒步旅行
他们在山里长途徒步，花了一整天。
一般过去时which 非限制性定语从句短语 go on a hike短语 a long hike
They went on a long ___ in the mountains, which took them the whole day.
第 3 题 · 高考
He planted some peas in the garden, which will grow into green plants.
核心词：pea piː n. 豌豆
他在花园里种了些豌豆，它们会长成绿色植物。
一般过去时which 定语从句短语 green peas短语 plant peas
He planted some ___ in the garden, which will grow into green plants.
