ago后面加什么时态
ago主要用于一般过去时，ago不能单独使用,应与three days(months,weeks)等连用,而且和动词的过去时连用。
The house was pulled down long ago.
那栋房子很久以前就被拆掉了。
Just a few years ago the picture was very different.
几年前的情况就大不相同。
I used to smoke but I gave up two years ago.
我过去抽烟，但两年前就戒了。
She gave up teaching three years ago.
三年前，她放弃了教学工作。
The cost is about half as much again as it was two years ago.
现在的价格比两年前提高约一半。
