A. freeing them from bacteria harmful B. to free them bacteria harmful C. to free them from harmful bacteria D. freeing them from harmful bacteriaĐoạn văn15/83Mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 13 to 18. freeing them from bacteria harmful to free them bacteria harmful to free them from harmful bacteria freeing them from harmful bacteriaGiải thíchChọn đáp án D