原则一:用作目的状语时,原则上要用不定式。1.When asked why he went there,he said he was sent there_____for a space flight.A.training B.being trained C.to have trained D.to be trained解析:由于进行航空飞行训练是他被派往那儿的目的,所以要用不定式,排除选项A和B。另外,由于“他”与“训练”为被动关系,所以选D。2._____this cake,you’ll need 2 eggs,175g sugar Principle one: for the purpose of adverbial, in principle, to use infinitive. 1.When asked why he went there, he said he was sent yet_____for a space flight. A.training B.being trained C.to have trained D.to be trained Analysis: Since he was sent to conduct aerial flight training Purpose, so use infinitives to exclude options A and B. In addition, because “he ” and “training ” for the passive relationship, so choose D. 2 ._____ this cake, you’ll need 2 eggs, 175g sugar