单选题 He has been studying here for three years, by next summer he ______.
A. will graduate B. will have graduated
C. will be graduated D. will be graduating

【正确答案】 B
【答案解析】[解析] 将来完成时主要表示将来某时将会发生的事情，一般要用表示将来的时间状语，如：by或before引导的介词词组或before引导的时间状语从句。