Its eyes are a striking amber color and have an alert and intelligent expression.

The eyes should be very dark, oval in shape, and have an alert and intelligent expression.

The young engineer, Spahn, moved slightly, an alert expression on his face.

The eyes are oval and dark, with an alert, keen expression.

With an alert and wary expression, Olav was half way across the floor to greet her.

Hemingway had turned his head, and was looking at him, an alert expression on his face.

Maura sat in his arms, an alert expression on her face.

He turned then and saw in the flickering firelight the strangely alert expression on John's face.

Or if so she died with a very alert expression.

The dwarf stepped into the room from the courtyard, an alert expression of worry on his face.