请教英语大师,为什么句子The man did not wake up until the bed had struck

he went to sleep 是一个过去时,在这个过去时之前发生的动作就要用过去完成时,表明他是先把东西放在了地板上,之后才去睡觉的.又如：
After he had finished his homework,he was allowed to go and play football.在他完成作业之后,他才被允许出去踢球.