1.   His expression became more serious as he listened to her story.

2.   His expression became serious as he listened to her story.

3.   His expression became very grave when we told him what had happened.

4.   His expression became increasingly sombre.

5.   It seemed to Melissa that the expression had become a shade less hostile.

6.   Now, as he looked at the old woman, his expression became soft, almost tender.

7.   But the expression is becoming androgynous, and the age seems to be creeping upward.

8.   But the longer you look, the creepier the expression becomes.

9.   In recent years, the expression has become familiar.

10.   Retroactive expressions of patriotism became more common in a culture growing complacent in its prosperity.