题干

在实验中经常遇到现象或效果不明显的问题,我们需要对实验进行优化改进,下列采取的措施合理的是(     )

A:在测量纸锥下落的速度时,为了方便时间的测量,选用锥角较小的纸锥

B:在探究平面镜成像时,为了使棋子的像清晰一些,用手电筒对着玻璃板照

C:在探究红外线的热效应时,为了使温度计示数变化明显,将玻璃泡涂黑

D:在估测大气压值时,为了便于弹簧测力计的测量,选用较大容积的注射器

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C

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    Last winter vacation, my brother got a set of bedroom furniture for his thirteenth birthday. When it arrived, I helped my parents moved the 1  furniture to the garage(车库). It was still in good condition. I thought it might be a chance for us to2 someone in our community. I started to search neighbors, anyone who 3 a bedroom set. Finally, my mom helped me call the local primary school. They told me about Jaila, the daughter of a poor single mother. I was given a telephone number and 4 and I soon found myself at Jaila's.

    The moment I went into Jaila's room, I knew I had taken on too big a task. When I pushed the old door open, it made a long high noise. But the door was nothing compared with the rest of the room. Some old paint was 5 the wall. One of the windows was 6. The bed was just a mattress(床垫)on the old carpet. It seemed that the room needed7 furniture — it cried — for a complete makeover(翻新).

    That day I spent at least an hour looking around and 8how I could possibly fixed the room. I had never painted a wall, let alone fixed a floor. The second day, I returned with a large group of helpers — my close friends. We went to collect everything needed door to door in our community. We replaced and repainted Jaila's room. We sweated in Jaila's house for more than ten hours every day that week.

    The moment we finished, we called Jaila into the room. She jumped, laughed and hugged each of us. I turned to Jaila's mother, and saw she had tears running down her face.

    "Anna," Jaila called my name 9Yes?""Welcome to my new room!"

    When we saw how happy Jaila and her mother were, our tiredness disappeared into thin air. We are really10 to make a special experience of changing someone's life.