He's said to be uncertain about his future.

据说他对他的前途没有把握。

You'll be uncertain about what it's telling you.

你会不确定它告诉你什么。

Other people might be uncertain about trying something new.

其他人可能会茫然尝试一些新的东西。

You may be uncertain about some of your coworkers and your boss.

可能会对一些同事或老板的态度不太确定；

When your site is completely new, it is difficult to obtain attention because readers and the media may be uncertain about your content or expertise.

当你的网页是新的，这很难去吸引注意力，因为读者和媒体们可能对你的文章和专业知识没有把握。