Mark the letter A, B, C, or D on your answer sheet to indicate the cor

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.    

I wasn't sure how Belinda would react because I ____ her long. 

• A. A. didn't know
• B. B. wasn't knowing
• C. C. hadn't been knowing
• D. D. hadn't known

Sự việc không biết rõ Belinda xảy ra trước, vẫn đang ảnh hưởng tới tình huống wasn't sure
=> D