suppose

Compared meaning: to think something is probably true (verb).

比较义项：对不确定的事情表达看法、猜测或认定（动词）。

• suppose 本词

  Expresses a cautious assumption based on reasoning, often with lingering doubt or a note of resignation; common in polite or slightly formal hedges like 'I suppose so'.

  表示基于推理做出的谨慎推测，往往还带着一丝疑虑或无奈的语气，常用于像“我想是吧”这样略显客套或正式的委婉说法中。

  I suppose you're right, though I still have my doubts.

  我想你是对的，不过我心里还是有些疑虑。

• think

  The neutral, everyday verb for stating a personal opinion without indicating how strong or certain the speaker feels; works in almost any context.

  是表达个人看法时最中性、最常用的动词，并不表明说话人有多确定或多强烈，几乎适用于任何场合。

  I think the meeting starts at ten, but I'm not completely sure.

  我认为会议是十点开始，不过我不是完全确定。

• believe

  Shows strong conviction or trust that something is true, often because the speaker trusts the source or has faith in it, not just a passing impression.

  表示强烈的确信或信任，认为某事是真的，往往是因为说话人信任消息来源或对此深信不疑，而不只是一时的印象。

  I believe every word she told me, because she never lies.

  我相信她说的每一句话，因为她从不撒谎。

• guess

  Expresses low confidence or a casual, resigned assumption, sometimes made without real evidence; common in informal speech, especially American English.

  表示信心不足、较随意甚至无奈的猜测，有时并没有真正的依据，常见于非正式口语，尤其是美式英语。

  I guess we're stuck here until the storm passes.

  我猜我们得在这儿等到暴风雨过去了。

Suppose, think, believe and guess all mean thinking something is probably true, but confidence differs. Suppose shows a cautious assumption. Think is the neutral, everyday word for an opinion. Believe shows strong conviction. Guess shows low confidence, a casual assumption. Believe can mean 'religious faith'.

这四个词在猜测或认定某事为真时意思相近，但确定程度和语气不同：guess最随意、最不确定，suppose带一点推测加无奈或客套的语气，think最中性平常，believe语气最强，强调信任或确信。这里不比较believe“信奉、笃信（宗教或主张）”的意思，也不比较guess作名词“猜测”的用法。

Compared meaning: to suggest something as a hypothesis (verb).

比较义项：假设，假定（动词）。

• say

  Mainly used in imperative or conditional form to set up a quick hypothetical for casual discussion; informal, common in everyday speech rather than writing.

  主要用于祈使句或条件句中，快速提出一个假设场景以供随意讨论；语气非正式，多见于日常口语而非书面语。

  Say you won a million dollars—what's the first thing you'd buy?

  假设你中了一百万美元——你最想买的第一样东西是什么？

• suppose 本词

  More formal, used to introduce a supposition treated as true for the sake of an argument or logical exercise, often followed by 'that'.

  语气更正式，用来引出一个为了论证或逻辑推演而暂且当作真实的假设，常与“that”连用。

  Suppose the train is late; how would that affect our plans?

  假设火车晚点了，那会怎样影响我们的计划？

Say and suppose both introduce a hypothetical for discussion. Say is casual and spoken. Suppose is more formal, common in logical reasoning. Say can also mean 'to speak'; suppose can also mean 'to guess'; those meanings are not compared here.

这两个词都可用来提出一个假设场景以供讨论，意思相近，但语气和用法有别：say 更口语化，suppose 更正式，常用于逻辑推演。这里不比较 say 的“说，讲”义，也不比较 suppose 的“猜想，认为很可能”义。