1.   As I read them over several times, I gulped, realizing the gravity of what was before me.

2.   It was then that I realized the gravity of the situation.

3.   It was after a somber group of officers loaded him onto an airplane that he finally began to realize the gravity of his situation.

4.   Several students said at first they did not realize the gravity of the situation, with some believing the gun was a fake.

5.   After realizing the gravity of its error, Hoover first tried to deter people from flying by attaching difficult conditions to the deal.