Accept
字面意思是接受，但它也可用来表达你不得不相信某件你不愿相信的事，接受某一事实，不就是相信吗？
例如：She'll never accept that her husband has been unfaithful.
Take sb's word for it.
相信我的话（没错的）。
例如： "Do you want to check for yourself?"
"No, I'll take your word for it."
Swallow
“吞”也能表达“相信”吗？细想一下，这个字还真有意思，“吞”速度比细嚼慢咽可快多了，因此，swallow表示“立马相信”。
例如：The kids told her a pack of lies and she swallowed the whole lot.
Buy
“买”如何会变成“相信”的，我想这里面大概有 sales person 的一份功劳。当然这个词只适合在非正式的场合下使用。
例如：We could tell him it was an accident, but he'd never buy that.