I had promised to send him an email I got home but I was so busy that I forgot to do so .
A. while
B. until
C. the moment
D. ever since
网友回答
A. while
B. until
(答案→)C. the moment
D. ever since
解析：这题考查连词的用法：the moment“一…就…”，句意是：我许诺一到家就给他发一份E-mail，但我太忙忘了。选C。