这几个词都有：推测，假定之意。但是用一定法有差别。
1.assume v. 设想，假定
指想当然地将未经证实的事当真，比较武断。
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。
You cannot assume that a speaker of English is ipso facto qualified to teach English.
你不能假定会说英语的人就有资格教英语。
Even assuming this to be in principle possible, it will not be achieved soon.
即使假定这在理论上行得通，它也不可能于短期内实现。
In this example we have assumed a unit price of$ 10.
在这个例子中我们已假定单价为10元。
Let us assume for a moment that the plan succeeds.
咱们暂时假设计划成功。
It is a misconception to assume that the two continents are similar...
关于这两块大陆相似的假设是一种误解。
Assume A knows B is guilty.
假定甲知道乙应负罪责。
Assuming it rains tomorrow, what shall we do?
假定明天下雨，我们怎么办呢？
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？
You can stretch your legs on the spacious decks, play games, swim and enjoy good food— always assuming, of course, that the sea is calm.(新概念3，P112)
你可以在宽敞的甲板上散散步，伸伸腿，玩玩游戏，游游泳，结识一些有趣的人们，品尝美味的食品——当然，只有（假定、假设）在海上风平浪静的时候才能如此。
注意:在assuming that之间加入了插入语of course；表示“当然只有假定、假设在……”
2.presume v. [正式] 假设，假定
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，但结论可能有误。
I presume you're here on business.
我想（推测）你是来这里出差的。
He was reported missing, presumed dead.
有报道说他失踪了，并推定已经丧生。
We must presume innocence until we have proof of guilt.
在证实一个人有罪之前，我们必须假定其无辜。
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。
The arrangement presumes that both lenders and borrowers are rational.
这一协议假定借贷双方都是在神志清楚的状态下签订的。
3.suppose v. [正式] 假定；猜想
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。
The company's plan supposes a steady increase in wheat yield.
公司的这个计划假定小麦产量会稳定增加。
What makes him suppose they're going to quit?
他凭什么认为他们要离职？
I suppose it has a certain novelty value.
我觉得这有一定的新意。
It is ingenuous to suppose that money did not play a part in his decision.
如果以为他的决定没有金钱的因素，那就太天真了。
I don't want to go to the party, but I suppose I'd better put in an appearance.
我不想去参加这个聚会，不过我认为最好还是去露个面。
Getting a visa isn't as simple as you might suppose.
办签证不像你想的那么容易。
She had supposed him (to be) very rich.
她原以为他很有钱。
I had supposed his wife a younger woman.
我原以为他妻子要更年轻。
I don't suppose for a minute that he'll agree.（否定前移）
我认为他决不会同意。
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。
I don't suppose (that) I could have a look at your newspaper, could I?
我能不能看看您的报纸？(用于婉转地提出请求)
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)
Suppose/Supposing 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？
Suppose/Supposing someone gave you an egg and asked you to describe exactly what was inside...
假设有人给了你一枚鸡蛋并要你准确描述鸡蛋里面有什么。