Mark the letter A, B, C, or D on...

Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following questions
South African anti-apartheid veteran Winnie Madikizela-Mandela, ex-wife of late President Nelson Mandela, _______ in and out of hospital since 2016 for back and knee surgery.

A. has been being

B. has been

C. was

D. had been