His customary remote expression had been replaced by one of keen interest.

The arrogant expression was replaced by a puzzled one as he looked up from the floor.

His happy-go-lucky expression had been replaced by one of mounting dread.

The sharp expression of interest left his eyes and was replaced with a muddy look of fear.

(iii) Any expression can be replaced by another one which is equivalent.

By the time he finally reached me, his public expression had been replaced by a look of genuine concern.

The Doctor's expression of amazement was replaced by a frown.

In the next moment that expression was replaced with recognition.

His expression of fear had been replaced by confusion.

The colonel's expression of determination was replaced by one of interest.