But if it's so obvious, how come for so long people have not realized it?

可是如果这一点真是那么显而易见，缘何长久以来人们就是意识不到呢？

youdao

But these harms actually have not realized by the people, or does not take seriously.

而这些危害却是未被人们意识到的，或不重视的。

youdao

When I first read this book, I thought "My god, how could I have not realized this before?"

当我第一次读这本书的时候，我在想，“天哪，我之前怎么没有意识到这些呢？”

youdao

Bill looked at his backside and realized that he did not have a tail like the other coyotes.

VOA: special.2011.06.11

By the way, that is a subtle thing people may not have realized.

顺便说一下有一个人们不曾发觉的微妙细节

耶鲁公开课 - 基础物理课程节选

This is something you guys may not have realized.

这一点你们可能没意识到

耶鲁公开课 - 基础物理课程节选

Though most Facebook users have been made aware of the fact that the new privacy settings default to be quite open, many have not realized that this applies to their photo albums too.

FORBES: Connect

But our worst fears (about Europe) have not been realized.

FORBES: Analysts Mixed On Gold Next Week; Technical Factors Cited Both Ways

Thankfully, the majority of online merchants have figured out that traffic to their site is essential to sales, but many have not yet realized that the user experience is equally as important.

FORBES: Cyber Monday Lessons: Apple Can Get Away with Outdated Mobile Sites...But You Can't