Keeping a diary is good habit by which you'll make great progress in writing.A. a; aB.

问题补充：

Keeping a diary is good habit, by which youll make great progress in writing.

A. a; a

B. a; 不填

C. the; a

D. the; 不填

答案：

A. a; a

(答案→)B. a; 不填

C. the; a

D. the; 不填

解析：考查冠词：第一空填a，a good habit一个好习惯，第二空不填，因为progress是不可数名词，句意：记日记是个好习惯，通过记日记你可以在写作方面取得进步。选B。