How long ago did you buy it?
这东西你是多久以前买的？
used in expressions of time with the simple past tense to show how far in the past sth happened (与动词简单过去时连用)以前:
60秒记一个单词（第1730个）ago
How long ago did you buy it?
这东西你是多久以前买的？
used in expressions of time with the simple past tense to show how far in the past sth happened (与动词简单过去时连用)以前:
