I'll bet you (that) he knows all about it.

我敢说他了解一切。

《牛津词典》

But I'll bet you would if it were easier.

但如果它更简单的话，我想您会去这样做的。

youdao

I'll bet you can guess what's coming next.

我想你一定知道接下来会发生什么。

youdao

And the sooner you learn -- get out.Get out!" MOTHER: "Mercy Maude,Frank, I'll bet you jumped six and nine-tenths inches that time."

VOA: special.2009.05.04

I'll bet you never heard of Tellus of Athens, neither had Croesus, neither had anybody else outside of Athens.

我打赌你们从没听说过雅典的特勒斯,包括克罗伊斯在内的,任何一个非雅典人都不知道

耶鲁公开课 - 古希腊历史简介课程节选

I'll bet you, even if you're reading this for the second or the third time, you were surprised again when you came to this point.

我敢说，即使是第二遍或第三遍读这首诗,读到这儿时你们还是会感到惊讶。

耶鲁公开课 - 弥尔顿课程节选

And I'll bet you, you're going to be heading out to that gardening store, right?

NPR: Vegetable Gardening On A Budget

And I'll bet you'll start seeing them play a bit better.

CNN: Brazile: But can the dude play?

But I'll bet you money, if he didn't have that hoodie on, that nutty neighborhood watch guy wouldn't have responded in that violent and aggressive way.

CNN: A fight for Trayvon Martin is a war against stereotypes