1.   An empty cab.

2.   Empty cabs will slide into the designated slots quickly and safely.

3.   I politely ask the cabby to move his empty cab, as there is nothing between his cab and the corner.

4.   Kavanaugh, a van messenger, said he took the day off after he saw the police refusing to let empty cabs cross the Manhattan Bridge.

5.   They tried to drive a cavalcade of empty cabs across the Queensboro Bridge.