Do you kown how long it's been since I've grabbed a spoon?这句

since从句中的动词grab是一个延续性动词,所以要从这个动作结束算起.如果是非延续性动词就从动作开始算起.注意下面例子
How long is it since you came here?你来这有多入了?9（came非延续性,从这个动作开始算起）
How long is it since you lived here?你不住这有多久了?（live延续性动词,从它结束算起） 这是since一词的特殊用法.