I suppose
You can say 'I suppose' when you want to express slight uncertainty.
I suppose I'd better do some homework.
我想我最好做点家庭作业。
'Is that the right way up?'—'Yeah. I suppose so.'
“那是上去的路吗?” “是的。我想是。”
You can say 'I suppose' or 'I don't suppose' before describing someone's probable thoughts or attitude, when you are impatient or slightly angry with them.
I suppose you think you're funny.
我想你认为自己很有趣。
I don't suppose
You can say 'I don't suppose' as a way of introducing a polite request.
I don't suppose you could tell me where James Street is, could you?
不知你能不能告诉我詹姆士街在哪儿?
do you suppose
You can use 'do you suppose' to introduce a question when you want someone to give their opinion about something, although you know that they are unlikely to have any more knowledge or information about it than you.
Do you suppose he was telling the truth?
你认为他说的是真的?
supposes , supposing , supposed
You can use suppose or supposing before mentioning a possible situation or action. You usually then go on to consider the effects that this situation or action might have.
Suppose someone gave you an egg and asked you to describe exactly what was inside.
假设某人给你一个蛋并要你准确描述里面的东西。
If you suppose that something is true, you believe that it is probably true, because of other things that you know.
The policy is perfectly clear and I see no reason to suppose that it isn't working.
这项政策非常明了,我找不到证明它行不通的任何理由。
I knew very well that the problem was more complex than he supposed.
我很清楚这个问题比他料想的更复杂。