—Did you write to Grace last summer?　　　　—No but Ill her over Christmas vacation.A. be s

问题补充：

—Did you write to Grace last summer?

—No, but Ill her over Christmas vacation.

A. be seen

B. have seen

C. be seeing

D. to see

答案：

A. be seen

B. have seen

(答案→)C. be seeing

D. to see

解析：本题使用将来进行时，表示按计划安排将来要执行的动作。