| 1 | The computer is now an indispensable tool in many businesses. | |
| 2 | He was the indispensable man of his era. | |
| 3 | But the real challenge to our notion of the "essential" father might well be the lesbian mom. | |
| 4 | While you may want to do the same on Monday, your presence is likely to be not only required, but essential. | |
| 5 | The firm is now as essential a component of the market' s infrastructure as the physical network itself, critics say. |