单选题 ______ you promise you will work hard, ______ support you to college.
A. If only...will I B. Only...I will
C. Only if...will I D. Only if...I will

【正确答案】 C
【答案解析】[解析] only if“只有”，用倒装；if only“但愿”，后用虚拟语气。所以本题选C。