单选题 I won't be able to play outside with you tomorrow because I ______ my homework at that time.
A. shall have done
B. will do
C. will be doing
D. shall be done

【正确答案】 C
【答案解析】at that time在句中指的是将来(某时)正发生着的事情，因而要用将来正在进行时。答案为C。