ad.以前
例句与用法:
1.He came here two years ago.
他两年前来到这里.
2.He joined the army a year ago.
一年以前,他参军了.
3.Long ago enormous animals lived on the earth.
很久以前,地球上生活着巨大的动物.
4.There were lots of buffaloes in the North America 100 years ago.
100年前,北美有大量的野牛.
5.All that happened many moons ago.
那一切都发生在很久以前.
6.The population has increased from 1.2 million 10 years ago to 1.8 million now.
人口从10年前的120万已增加到现在的180万.
7.They were supposed to be here an hour ago.
他们应该在一小时以前到达这里.
8.It happened quite some time ago.
那是很久以前的事.
形容词ago:
1.gone by; or in the past
同义词：agone
副词ago:
1.in the past