Financial problems became serious enough for Sherman to sell the company to the city government in the 1920s.

He glanced away from the road and became more serious.

But it is clear that the talks have become serious.

After six weeks of this I think we both thought that things were becoming pretty serious.

Also, he was becoming serious about his dream of writing.

Talk about the need for a European central bank is becoming more serious.

But one of his best friends is in a relationship that has become increasingly serious.

So we became serious and hung out together nearly every day.

In the short time since then, the situation has become more serious.

There he finally seemed to settle down and became serious.