The nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius in two letters to the historian Tacitus.
(C)The only eyewitness account is in two letters by the nephew of Pliny the Elder writing to the historian tacitus an account of the great eruption of Vesuvius.
ETS 是這樣解釋: the sentence's meaning is unclear due to an extended sequence of prepositional phrases.
請問劃線部分的解釋是什麼意思呢?
還請版上的朋友多幫忙....