I'd certainly tell you if I knew anything, but I don't. What you're saying is news to me.

我要是知道点儿什么，我肯定告诉你，可我不知道。你现在说的对我还是新闻呢。

《柯林斯英汉双解大词典》

"I would ban that too if I knew the students were using it in class," Professor Summers said of the iPhone, after the device and its capabilities were explained to him.

“如果我知道学生们在课堂上使用它，我也会禁止使用它。”萨默斯教授在了解了苹果手机及其功能后，这样评价它。

youdao

They asked if I knew anyone who could help them.

他们谁都不会说俄语，于是问我，是否认识什么人能帮他们的忙。

youdao

"If I knew how to answer this question, he would not have been at large,"

VOA: standard.2009.10.25

Conversely, if I knew the velocity of this object, I also know what time it is, provided I knew the initial velocity.

反过来,如果我知道了这个物体的速度,我也同样可以知道时间,只要初速度是已知的

耶鲁公开课 - 基础物理课程节选

and I knew if I wanted to be good, as good as I wanted to be, I needed to come here.

而且我知道，如果我想变得更好，变得和我想的一样好，我就得到这里来。

和纽约的留学生 - SpeakingMax英语口语达人

But then, my mind could be changed if I knew more about the technology.

BBC: News Online

Trust me, if I knew that, I would, shall we say, be in a better place.

WHITEHOUSE: Press Briefing

But if I knew I could call in and not be put on hold forever, I'd call.

CNN: We Work For You!