2010年高考英語語法精講十六：時態的綜合問題
在說或寫一句話時，通常要選擇一個中心時態，這個中心時態影響其它時態 ，即時態要前后一致。
以現在為中心：若開始敘述或描述著眼于現在，則常以現在為起點，從而會出現一般現在時、現在進行時、現在完成時或一般將來時連用的情況。
Our postman usually delivers our arrival at 7 every morning. It (be) nearly lunchtime and the mail still (not arrive). I (suppose) the mail (come) soon. Perhaps he (be) ill. (is, hasnt arrived, suppose, will come, is
以過去為中心：若著眼于過去，則常以過去某時為基點，從而出現一般過去時、過去進行時、過去將來時和過去完成時連用的情況。
We lived in the street. They (build) houses all around us then. We (be) there for 10 years and (imagine) we (stay) there for the rest of our lives. (were building, had been, imagined, would stay)
