Represent the following sentence by a Boolean expression: “In a battery-powered computer, the disk drive motor 1 should be on if and only if (a) There is a disk in the drive, and (b) The disk drive is closed, and (c) The disk drive motor 2 is not on, and (d) The battery low signal is not present, and (e) The computer has started a read operation, or the computer has started a write operation.”