it seemed only several minutes before he finnished this painting 翻译

您一定要 解释清楚一下 before的用法 还有为什么不可以填 when

It seemed only severval minutes___ he finished this painting. It seemed to me that the only thing that matters is to learn through failure. It seemed as if...是什么意思？ It seemed unlikely to me,but our class teacher seemed absolutely ___ about it. she seemed to be sleeping=she seemed to sleep.=it seemed that she is sleeping.吗? It seemed that he had been told all ------. Only after what seemed a long time did rescue come to him Only after what seemed a long time did rescue come to him . it only the fairly tale In the days__,he was still in low spirits,and it seemed hard for him to get over it