when是可以引导让步状语从句，此时when兼有时间和让步（although）的含义。表示“虽然……却（但是）”“尽管……但”；“本（可以，应该）……却”，分两种情况说明：
1. “虽然……却（但是）”“尽管……但”；
Bob always goes a long way when he might take a short cut. 鲍勃虽有近路可走，却总是走远路。
He walks when he might take a taxi. 他虽然可以乘出租车，却总是步行。
They have only three copies when we need five. 尽管我们需要五本，但他们只有三本。
You describe this policy as rigid an inflexible, when in fact it has been flexible.
你把这项政策说成是僵硬而毫无灵活性的，而事实上它是极其灵活的。
They kept trying when they must have known it was hopeless.
他们虽然明明知道已没有了希望，但是他们仍然继续努力。
2.本（应该，可以）……却（when分句使用虚拟语气）
She stopped when she ought to have continued. 尽管她本应该继续下去，她却停住了。
She paid when could have entered free.她本来可以免费入场，而她却付了款。
She stopped trying when she might have succeeded next.
她本来下次有可能成功，而她却不再尝试了。
They were gossiping, when they should have been working.
他们本该工作，却在那里说别人的闲话。
She cleans the house by herself, when she could easily have asked her children to help her.
她本该可以很容易地让孩子们来帮忙，却还是亲自动手清理房间。
3.while/when引导的让步状语从句的区别
while, when也可以用作从属连词表让步，while常用于句首，when常用在句中。例如：
While I admit that there are problems, I don't agree that they cannot be solved. 尽管我承认有问题存在，但我不同意说这些问题不能解决。
While I am willing to help, I do not have much time available. 尽管我愿意帮忙，但是没有多少时间。
While the Internet is bridging the distance between people, it may also be breaking some homes or will cause other family problems.
虽然互联网正在拉近人们之间的距离，但它也可能破坏一些家庭，或者会引发其他家庭问题。
They kept digging when they must have known there was no hope. 虽然他们明知没有希望，但还是在不停地挖。
She claimed to be 18, when I know she's only 16. 她自称是18岁，虽然我知道她才16。