问题补充：
David apologized for to inform me of the change in the plan.
A. his being not able
B. him not to be able
C. his not being able
D. him to be not able
答案：
A. his being not able
B. him not to be able
(答案→)C. his not being able
D. him to be not able
解析：考察动名词的复合结构。固定搭配apology to sb for sth因为某事向某人道歉。本句中的for是介词，后面要接动名词doing的复合结构，句意在动名词前面加上not表示否定式，也可以在前面加上宾格或者所有格形成复合结构。句意：David因为没有通知我计划的改变而向我道歉。故C正确。
