这个when引导的是一个（和先行词隔开的）定语从句，不是主语从句。
英语句子中出现这种分隔现象的原因是主语或宾语带了过长的修饰成份。为了照顾主句结构紧凑，保持句子平衡，就常常将先行词和定语从句隔开，这样的定语从句就叫分隔式定语从句。例如：
The days have gone forever when the Chinese were looked down upon and bullied. 中国人被人歧视、欺凌的日子一去不复返了。（when的先行词是the days，被主句谓语 have gone forever分隔开了)
They still remember one afternoon in the first year when the professor took the students to the chemistry lab．他们仍然记得一年级时教授带他们到化学实验室的那个下午。(when的先行词 是one afternoon，被用作定语的短语in the first year分隔开了)
I was the only person in my office who was invited. 我是我们办公室里唯一被邀请的人。(who的先行词 是the only person，被用作状语的 in my office分隔开了)
In 1898, a law was passed which meant all people above a certain age were paid a weekly “old age pension". 1898年，通过了一项法律，规定一定年龄以上的人都按周付给“养老金”。(which的先行词 是a law，被主句谓语 was passed分隔开了)。
英语句子中出现这种分隔现象的原因是主语或宾语带了过长的修饰成份。为了照顾主句结构紧凑，保持句子平衡，就常常将先行词和定语从句隔开，这样的定语从句就叫分隔式定语从句。例如：
The days have gone forever when the Chinese were looked down upon and bullied. 中国人被人歧视、欺凌的日子一去不复返了。（when的先行词是the days，被主句谓语 have gone forever分隔开了)
They still remember one afternoon in the first year when the professor took the students to the chemistry lab．他们仍然记得一年级时教授带他们到化学实验室的那个下午。(when的先行词 是one afternoon，被用作定语的短语in the first year分隔开了)
I was the only person in my office who was invited. 我是我们办公室里唯一被邀请的人。(who的先行词 是the only person，被用作状语的 in my office分隔开了)
In 1898, a law was passed which meant all people above a certain age were paid a weekly “old age pension". 1898年，通过了一项法律，规定一定年龄以上的人都按周付给“养老金”。(which的先行词 是a law，被主句谓语 was passed分隔开了)。
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第1个回答 2015-11-16
状语从句。其实，判断从句是什么类型只要知道整个句子在主干句中做什么成分就行了。主干句time is approaching，主谓宾都不缺，when又表时间，故而引导的是时间状语从句。
第2个回答 2015-11-16
状语从句吧
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