He was as dead as a mackerel.

She was as merry as a grig at the party.

She felt snug as a bug in her cozy sweater.

She looked as smart as paint in her new dress.

The old house was as empty as a pauper's purse.

He was asleep at the wheel and caused a car accident.

The identity of the mysterious figure remains as yet unknown.

There are still many as-yet-unknowns in the field of science.

The identity of the culprit is as-yet-unknown.