Mark the letter A, B, C, or D to indicate the correct answer: __ umbrella shouldĐoạn văn31/39Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions. ____ umbrella should not be used during ______ thunderstorm.a/athe/aan/ano article/ aGiải thíchĐáp án C.