选C
A."一天天地,逐日地"
B选项——from day to day才是“日复一日”的意思.
C,day after day "日复一日地"
D.没有day and day ,只有day and night意思是“夜以继日地”
day by day和day after day在意思上区别不大,一个意为逐日、日渐,一个意为日复一日.
其差别主要在用法上.
1.day by day强调程度的递变,强调有变化.(含有越来..越..之意）
His English gets better day by day.
2.day after day用于形容动作的重复.（不含变化的意思）
He goes to look after his grandfather day after day.
(他天天都去看他的祖父）
本题中说“他每天都在门口等着儿子归来”强调动作重复而且是日复一日的.故选C