| a. | None of the astronomers saw the comet, /but John did. (Available verb phrase) |
| b. | Seeing the comet was nearly impossible, /but John did. (Embedded verb phrase) |
| c. | The comet was nearly impossible to see, /but John did. (Verb phrase with trace) |
| d. | The comet was nearly unseeable, /but John did. (Negative adjective) |