last month是什么时态

　　An old Roman vase was dug up here last month.

　　上个月在此地出土了一个古罗马花瓶。

　　Nick's grown almost an inch in the last month.

　　尼克这一个月来长高了差不多一英寸。

　　A new constitution was promulgated last month.

　　上个月颁布了一部新宪法。

　　He deserted from army intelligence last month.

　　他上个月从军队情报部门开了小差。

　　Unemployment dipped to 6.9 percent last month.

　　上个月，失业率降到了6.9%。

　　The commission concluded its investigation last month.

　　委员会在上个月终止了调查。