An empty category (EC) refers to a nominal element that is phonetically null (or unpronounced). Four types of EC are generally identified in the generative linguistic literature, i.e., NP-trace in the raising construction (1), wh-trace (sometimes called "variable") in the wh-question (2), pro in the null subject (sometimes null object) construction (3), and PRO in the control construction (4).
| 1. | Johni seems [ ti to like linguistics very much]. |
| 2. | Whomi does Bill like ti? |
| 3. | pro ha parlato. (Italian) |
|
| has spoken.3sg |
| 4. | Johni plans [PROi to visit his aunt next week]. |
The…