2018年考研英语二真题句子解析： When left alone in the room, the students who did not know which ones would shock them clicked more pens and incurred more shocks than the students who knew what would happen.

When left alone in the room

时间状语从句"When left alone in the room"省略了主语"the students"和系动词"were",完整形式为"When the students were left alone in the room"。这种省略的条件是:从句主语与主句主语相同,且从句谓语含be动词。省略后句子更简洁,但需要还原才能完整理解句子结构。

When left alone in the room

"left"是过去分词,在此作时间状语从句中的谓语成分。完整形式应为"When (the students were) left alone",省略了主语和be动词。"left"表被动含义(学生"被留下"),修饰整个主句动作发生的时间背景。过去分词作状语时,其逻辑主语必须与主句主语一致,这里都是"the students"。

the students who did not know which ones would shock them clicked more pens

主语"the students"与其谓语"clicked"之间被长定语从句"who did not know which ones would shock them"分隔开。定语从句长达9个词,且内部还嵌套了宾语从句"which ones would shock them",使得读者需要跨越较长距离才能找到主句的核心谓语动词。这种分隔增加了句子理解难度,需要识别定语从句的边界才能准确定位主干。

the students who did not know which ones would shock them

第一层:定语从句"who did not know which ones would shock them"修饰"the students";第二层:宾语从句"which ones would shock them"作"know"的宾语,嵌套在定语从句内部。这种从句套从句的结构形成两层嵌套,定语从句和宾语从句各司其职,构成典型的嵌套关系,增加了句子的复杂度。

the students who knew what would happen

"what would happen"后面省略了完整表达,对应前文"which ones would shock them"的内容。完整还原应为"knew what would happen (when they clicked the pens)"。这里省略了已在上下文明确的内容,避免重复,但理解时需要补全这层含义才能把握句意对比关系。