Suggested answer for Exercise 4

Jim’s boat was sunk is a passive sentence. The main verb is sink, occupying the V head in the D-structure. Now v is not occupied by an abstract light verb as in (4) but by the passive morpheme en. The main difference between a light verb and the passive morpheme is that the passive morpheme does not take an agent argument and it cannot assign Case to the DP occupying the specifier position of the VP. Since the DP has to receive Case, it has to move to the specifier of IP, where the finite I head assigns nominative Case to it. The passive morpheme in v is a bound morpheme, so the main verb is required to adjoin to it. The other vP in the structure is the tense vP where be is inserted to support the past tense morpheme (remember, in English a thematic verb is not allowed to have more than one inflectional morpheme, so it cannot move to support a second bound morpheme after having moved to the passive vP). Finally, the verb ends up in the I head position.