不曉得你想說什麼事情上次發生。如果能明確事情，把這個事情作為主語說出來會比較明確。個人見解，如果不好說也可以說It happened a month ago.

An old greek statue was dug up here last month ..

上個月在這兒挖出了一尊古希臘雕像。

Last month he was sentenced to 5～15 years in prison .

上個月他被判處五年至十五年徒刑。

He came here last month .

他是上月來這裡的。

Taylor 's business just managed to break even last month .

上月泰勒的生意收支平衡，不虧不盈。

I got engaged last month .

我上個月訂婚。

The average temperature in oxford last month was 18 centigrade .

牛津上月的平均氣溫是18攝氏度。

The number of cars stolen in this city last month ran into 60 .

這個城市上月被盜汽車的數目達到60輛。

Last month he suffered a heart attack. but now he seems to have bounced back .

上月他心髒病發作過一次，但看來現在已復元了。

I have been watching you closely during the last month or two and i'm very pleased with your work .

在前一，二個月裡，我一直在仔細地觀察你，我對你的工作很滿意。

The commission concluded its investigation last month

委員會上個月終止了調查。