Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word for each of the blanks from 51 to 60. It was test day in Mr. Koch’s class. Everyone was (51) _________ reading and filling in answers on their test papers. Suddenly Richard (52) _________ . He had seen something move, no scurry, across the classroom floor from the corner of his eye. Or had he? He thought perhaps he just imagined it  and went back to (53) _________ on his test. Then, a moment later, there it went again, this time in the other direction. toward the door. He still wasn’t sure what he (54) _________ , but he was sure he had seen something. He considered telling Mr. Koch, but thought he'd better not disturb the group during a test. He tried to keep his mind focused on identifying the parts of speech in the passage he (55) _________ , but it kept returning to the "thing” he saw. (56) _________ it was a rat?” he thought with distaste and concern. He found himself scanning the floor every few seconds in (57) _________ of catching another glimpse of it and settling his imagination down into reality. It did not reappear the (58) _________ of the period. At lunch he told his friends about the mystery sighting and his fears that it (59) _________ a rat, or a mouse at the very least. The school could be infested! At that suggestion, a few of them automatically raised their feet and looked down. Mary just sat there with a wide grin. She let them speculate for awhile, then told them how one of the hamsters kept in Miss Moore’s room had gotten (60) _________ that morning, but came back to the room shortly after his adventure.   Trả lời câu hỏi dưới đây:________ (61)