It was x a difficult question that they couldn't explain21/80 Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions. It was x a difficult question that they couldn't explain. such so very tooGiải thíchĐáp án là A. Cấu trúc: It + be+ such + N + that + S+ V…: quá… đến nỗi ....