怎样分辨would与used to在用法上异同

Would与used to都可用来表示过去经常性或习惯性的动作，常常可以换用。如：

(1)When we were boys we used to/would go swimming every summer.

小时候，每到夏天我们都要去游泳。

(2)He used to/would spend every penny he earned on books.

过去，他通常把挣来的钱全花在买书上。

Would与used to都不能用来表示动作发生的具体频度或具体的一段时间。例如，不能说：

(3) I would/used to go to France six times.

(4)He used to live in Africa for twenty years.

上两句应改成：

(5)I went to France six times. 我去过法国6次。

(6)He lived in Africa for twenty years. 他在非洲住过20年。

Would与used to的区别主要有以下几点：

a. Used to可指过去的状态或情况，would则不能。如：

(7)School children used to know the story of how Abraham Lincoln walked five miles to return a penny hed overcharged a customer.(不能用would)

过去，学校的孩子们都知道亚伯拉罕。林肯怎样步行5英里退还多收顾客1便士的故事。

(8)Yet，he cannot but remember China as it used to be.然而，他不会不记得旧日的中国(不能用would)。

b. Would表示反复发生的动作。如果某一动作没有反复性，就不能用 would，只能用 used to.例如：

(9) And from that day on， as soon as the table was cleared and the dishes were gone. Mother would disappear into her sewing room to practice.

从那天起，只要碗盘撤掉、饭桌一清理干净，妈妈就马上躲进做针线活的房间练习起来。(具有反复性)

(10)I used to live in Beijing. 我过去住在北京。(没有反复性)

c. Used to表示过去经常性或习惯性的动作或状态现在已经结束，would则表示有可能再发生。如：

(11)People used to believe that the earth was flat.

过去，人们总以为地球是扁平的。(现在已不再这样认为)

(12)He would go to the park as soon as he was free.

过去，他一有空就去公园。(现在有可能再去)

注意：used to的否定式和疑问句：

(13)过去我不喜欢歌剧。

I used not to like opera.

I usednt to like opera.

I didnt use to like opera.

(14)过去你喜欢歌剧吗?

used you to like opera?

Did you use to like opera?

(15)Didnt you use to like opera? 你过去不喜欢歌剧吗?

(16)You used to like opera， didnt you? 你过去喜欢歌剧，是吗?

(17)There used to be a church here， usednt there? 过去这里有座教堂，是不是?