until和before有什么区别？

until/not until是指：直到什么时候为止...其中非延续性动词用后者，延续性动词用前者。 例句：Not until my father came back did I fell asleep. I was awake until my father came back. 注意：倒装时倒装主句，从句语序不变。改为强调句时基本语序不变。 before在...之前，常用在时间状语从句中。 常用句型：It is +( )+before... 注意：前后时态要一致，遵从主