这个三个词都有：推测，假定之意，但是，含义和用法却大不相同。

1.assume v. 设想，假定，以为，推定

指想当然地将未经证实的事进行设想、假定或推测，比较武断。如：

I didn't see your cell phone, so I assumed you'd left.

我没看见你的手机，所以我以为你离开了。

People assume they know me through and through the moment we meet.

人们一见到我，就自以为对我了如指掌了。

Putting two and two together, I assume that this was the car he used.

根据我的了解，我猜想这是他曾开过的车子。

If the package is wrapped well, we assume the contents are also wonderful

如果包装精美，我们就会认为里面装的也是好东西。

I hope to go to college next year, always assuming I pass my exams.

我希望明年上大学，当然是在我通过考试的前提下。

Assuming that Dad agrees, when do you want to shop for a new car?

假设爸爸同意，你打算什么时候买新汽车？

Assume A knows B is guilty.

假定甲知道乙应负罪责。

Assuming he's still alive, how old would he be now?

假定他还活着，现在有多大年纪了？

I naively assumed that I would be paid for the work.

我天真地以为这活儿是有报酬的。

He assumed, wrongly, that she did not care.

他误以为她并不在乎。

It would be rash to assume that everyone will agree with you on this.

你要是认为在这件事上谁都会同意你的看法，那就太欠考虑了。

I had assumed him to be a Belgian.

我本以为他是比利时人。

I assume that you have heard the news. 料想你已经听到了那个消息。

I assumed that you had known the result.

我假定你已经知道了结果。(虽然我没证据，但我后续所有的行为都基于此假定)

I assume they will wait for us.

我假定她们会等我们。(我不知道真的会不会，但我以她们会等作为前提)

2.presume v. [正式]假设，假定；相信；料想，认为

常指以已有的经验、信息等为依据进行合乎逻辑的推测、推断，有信心有证据的基础上的假定；但结论可能有误。如：

I presumed (that) he understood the rules.

我相信他明白这些规则。

I presumed him to be her husband.

我料想那就是她丈夫。

This logical analysis presumes the separation of subject from object.

该逻辑分析假定主体与客体是分开的。

I presume that this price includes all transportation and accomodation fees.

我猜测，这个价钱包括一切交通费用和住宿费。

I presume you're here on business.

我想你是来这里出差的。

I would never presume it would be ok for people to hug the Queen.

我从来不认为我们可以拥抱女王。

3.suppose v. [正式]假定；猜想，推断，认为，料想，设想，假设

指在某一前提条件下或根据已有知识、信息等进行推测，有时用于表达意见。

基于一些证据的猜测(认为)。暗含着自己对对方所说的话信心不足，但自己目前无法证明对方是错误的。另外也有假设的意思。通常的用法是自己 suppose其他人。如：

I suppose your presence here today is not entirely coincidental.

我认为你今天来这里不完全是碰巧。

These new friends of hers are supposed to be very rich.

她的这些新朋友想必都很富有。

Well, I suppose I could fit you in at 3.45.

好吧，我想可以在3:45见你。

Prices will go up, I suppose.

我觉得物价将会上涨。

I suppose someone had to do it. (This is just what I guess. I may be wrong)

我猜有人要去做这件事(只是表达猜测，没有把握)

I should suppose him to be about sixty. 我猜想他大约60岁左右。

Let's suppose that he is right. 让我们假定他是对的。

I had supposed his wife a younger woman.

我原以为他妻子要更年轻。

She had supposed him (to be) very rich.

她原以为他很有钱。

I don't suppose for a minute that he'll agree.

我认为他决不会同意。

Suppose we take a later train?

要不我们坐晚一点的火车？

Suppose （that） flights are fully booked on that day─which other day could we go?

假定那天的航班都订满了——我们还可以在哪天走呢？

I suppose you think you're funny...

我想你认为自己很好笑。(表示不耐烦或有些生气)

I don't suppose I could have a look at your newspaper, could I?

我能不能看看您的报纸？

I don't suppose you could tell me where James Street is , could you?

你能否告诉我詹姆斯街在哪儿？ (用于婉转地提出请求)

Do you suppose he was telling the truth?...

你认为他说的是实话吗？ (用于询问意见)

Do you suppose we could get together for a little chat sometime soon?

我们最近能抽空聚在一起聊上几句吗？(用于礼貌地建议或请求)