Glass that has been tempered may be up to ________.Đoạn văn24/55IV. WRITINGFrom the words or phrases - a, b, c or d - choose the one that best completes the sentences.Glass that has been tempered may be up to ________.as hard as ordinary glass five timesfive times as hard as ordinary glasshard as ordinary glass five timesordinary glass as hard as five timesGiải thíchĐáp án đúng là b