【正确答案】 C

【答案解析】[解析] 考查疑问词+不定式结构。疑问词who，what，which，when，where和how后加不定式可构成一种特殊的不定式短语。它在句中可以用作主语、宾语、表语和双宾语等。(1)作主语：When to start has not been decided. (何时动身尚未决定。)(2)作宾语：I don't know what to do. (我不知道该怎么办。)(3)作表语：The difficulty was how to cross the river. (困难在于如何过河。)(4)作双宾语：I call tell you where to get this cake. (我可以告诉你哪儿可以买到这种蛋糕。)本题考查该结构作宾语的情况。