一般来说,时间上前后应该一致,前面是现在时,后面也是现在时,前面是过去时,后面也是过去时.表示将来时间的（will do,be going to do,be donging,be to do,be about to do等等）本身只是现在时的一种变体,不妨看作现在时.但如果用了before,after等表示前后的连词时,动作时间相对于说话时间是同时的还是过去的要根据意思来判断,“时”就可能不一致了,如：After Mary died last week,the family is now in deep sorrow.又如：Before I say these words,I didn't tell anyone.