Happily, his neck injuries were not serious.

幸运的是，他脖子上的伤并不严重。

The problems are not serious. Nonetheless, we shall need to tackle them soon.

问题不严重，不过我们还是需要尽快处理。

We were greatly relieved to learn that his condition was not serious.

听说他的病情并不严重， 我们的心就宽多了。

You know I'm not serious, right?

你知道我只是说说而已，对吗？

That's not serious!

那也不重要。