前面不用介词，例如：
1、How long ago did you buy it?这东西你是多久以前买的
2、The house was pulled down long ago.那栋房子很久以前就被拆掉了。
3、Just a few years ago the picture was very different.几年前的情况就大不相同。
4、I used to smoke but I gave up two years ago.我过去抽烟，但两年前就戒了。
前面不用介词，例如：
1、How long ago did you buy it?这东西你是多久以前买的
2、The house was pulled down long ago.那栋房子很久以前就被拆掉了。
3、Just a few years ago the picture was very different.几年前的情况就大不相同。
4、I used to smoke but I gave up two years ago.我过去抽烟，但两年前就戒了。
