I should have known the answer to his simple question.

我本应该知道他那个简单问题的答案的。

youdao

I should have known earlier.

我应该早点知道这些。

youdao

Oh, I should have known it.

哦，我早该想到的。

youdao

I shouldn't havebrought you here. I should have known it was goingto be some bullshit hassle!

VOA: standard.other

Some of the things I said--you'd probably say, well I should have known that an insurance company would have to do that, but it isn't.

对于我说的一些东西，你可能会说，我早就知道,保险公司会如此操作，但事实并非如此。

耶鲁公开课 - 金融市场课程节选

I should have known better.

我早该知道的。

I should have 课堂 - SpeakingMax英语口语达人

After decades of work in radio, music and popular culture, I should have known better.

FORBES: Tribune's Lee Abrams Defends Himself: "I Will Not Stop Pushing"

Amazing to think that I lay awake worrying about him, when I should have known in my silly heart that I was for the chop.

NEWYORKER: Hand on the Shoulder

Mr. RONNIE HOLMES (Firefighter): I think they should have known better.

NPR: Responsible Consumers Decry Mortgage Bailout