【题目】The boat sank quickly but________ everybody was rescued.
A.generally
B.thoroughly
C.naturally
D.fortunately

【答案】D
【解析】A．generally总的来说；B．thoroughly完全地；C．naturally自然地；D．fortunately幸运的是；句意：船下沉的很快，但幸运的是每个人都获救了。根据句意，故选D。