1.   Everybody knew at once how serious the situation was.

2.   Everyone knew at once how serious the situation was.

3.   Everyone knew immediately how serious the situation was.

4.   How hard writing was for each of us was a gauge of how serious we were.

5.   How serious must the harm be?

6.   I knew he now realized this was serious, but I was not sure I had got through to him how serious.

7.   Secondly, just how serious is this man?

8.   Social scientists have devised a check-list of stressful events, weighted according to how serious they are.

9.   The attempt at adding-machine accuracy shows how serious the priests were about numbering the new saints bound for heaven.