英語時態(tài)的前后一致

時態(tài)的前后一致（The Sequence of Tenses）是指在說或寫一段話時，通常要選一個中心時態(tài)。如果開始敘述或描寫的時態(tài)著眼于“現(xiàn)在”，則通常以“現(xiàn)在”為基點從而出現(xiàn)下列時態(tài)的連用情況：

Our milkman usually delivers our milk at 6 o'clock every morning. It's nearly10o'clock am and the milkman still hasn't arrived. I suppose the milkman will come soon. Perhaps our milkman is ill.送牛奶的人每天早晨6點送牛奶來?，F(xiàn)在快到上午10點了，牛奶還沒有送到。我想快來了。也許是送牛奶的人生病了。
It's reported that the new railway is going to be built next year.據(jù)報道明年那里要建一條新鐵路。
I expect you will have changed your mind by tomorrow.我預料到明天你就會改變主意了。
如果開始敘述或描寫的時態(tài)著眼于“過去某時”，則通常以“過去某時”為基點從而出現(xiàn)下列時態(tài)的連用情況：

When I lived in Beijing the milkman usually delivered our milk at 6 o'clock every morning. Usually no one in our household had got up when the milk man arrived.我住在北京時，送牛奶的人每天早晨6點送牛奶來，那時我們都還沒有起床。
We hadn't expected that you would come so early.我們沒有料到你們會來得這么早。
She said they would have got everything ready by tonight.她說到今晚一切都會準備就緒。
“時態(tài)一致”這一概念應表述為：現(xiàn)在時通常與現(xiàn)在時連用；過去時通常與過去時連用。