求英语大神帮我看看这两句从句哪个对old people have rich experience,which we can learn the past.old people have rich experience from which we can learn from the past.其实我想知道的是我在书上看到这句话：old people have rich experience from which young people can learn form past mistakes.我觉得有点怪怪的 不明白为什么要用两个from 这句话本身正确吗

求英语大神帮我看看这两句从句哪个对
old people have rich experience,which we can learn the past.
old people have rich experience from which we can learn from the past.
其实我想知道的是我在书上看到这句话：old people have rich experience from which young people can learn form past mistakes.我觉得有点怪怪的 不明白为什么要用两个from 这句话本身正确吗