这句before后面从句时态的用法是怎么回事?you must first establish the primary cause of waste generation before attempting to find solutions.

这句before后面从句时态的用法是怎么回事?you must first establish the primary cause of waste generation before attempting to find solutions. before 引导的状语从句中如果主句是完成时 那从句用什么时态?since用法具体怎么用呢 it was 和it is +before这两个的时态要注意吗it is 3 years before they.和it was 3 years before they.从句主句后面的时态怎么用 before 引导的从句,后面时态怎么用?We decided it would be best to go home before our money_______.(run out)这句话应该用什么时态?为什么呢?用将来时的话，前面的是we decided是过去时，要考虑时态一致吗？如 这句话时态不对吧?they must have been several hundred people present just before the show began.后面那句是过去时,但是前面那句是现在完成时,连着现在的,怎么可能before? 连词before,until,while,as,since,as soon as,after的用法时态方面的 例如 主句 是 一般现在时 从句是什么时态?还有别的时态 after从句?after后面是从句,时态怎么用? 宾语从句的时态 用法 ? 请告诉我一下after和before的用法,后面接的东西和时态, 宾语从句,状语从句,定语从句与主句的时态用法是相同的吗 宾语从句的时态是怎么变化 when引导的时间状语从句和宾语从句的时态RT.Please讲解一下下时态!主要是在句中的时态问题,比如：在when引导的时间状语从句中when之前的主句是什么时态,后面的从句是什么时态的.宾语从句也 when的主.从句的时态用法 when的主.从句的时态用法 they sat down opposite each other ,but it was some moments before they spoke此句怎么翻译?为什么后面的从句中要用before?翻译不顺啊 I think the calculator was invened before the computer.是什么从句,主从句的时态是?the calculator与invent是_____关系, consider的从句后面用什么时态? make sure that的用法请问make sure that后面的从句要跟什么时态?有一个改错题Make sure that you will attend my birthday party.答案是把will去掉，这又是为什么呀？