21. The young man made a ______ to his parents that he would try to earn his own living after graduation. (A). prediction (B). promise (C). plan (D). contribution

79.Why are some people worried about RFID technology? (A).Because children will be tracked by strangers. (B).Because market competition will become more fierce. (C).Because their private lives will be greatly affected. (D).Because customers will be forced to buy more products.