If you be there before 10 you have to say goodbye to each other and set off now.A. are to

问题补充：

If you be there before 10, you have to say goodbye to each other and set off now.

A. are to

B. are about to

C. will

D. will be going to

答案：

(答案→)A. are to

B. are about to

C. will

D. will be going to

解析：if引导的条件状语从句中不能用将来时态表将来，be to相当于must, have to 所以选A。