He has been silent on the subject for too long now.
Both women were silent on the phone for a minute.
It was very silent on the other side of the door.
The room was silent on the matter of the lives which had passed through it.
She let him lead her to the car, but was silent on the short drive.
In recent years, he has been silent on this issue.
For various reasons, however, the Report was silent on the subject.
He had been silent on the matter for some time.
She would speak for that when silent on all else.
She had been silent on the subject of stars for too long.