根据短文理解，选择正确答案。

    Frederick was ill and went to the hospital. A doctor looked him over and said, "Well, Mr Green, you're going to get some injections(针), and you'll feel much better. A nurse will come and give you the first this evening, and you'll have to get another one tomorrow evening.'' In the evening a young nurse came to Frederick's bed and said to him. "I'm going to give you your first injection now, Mr Green. Where do you want it?"

    The old man was surprised. He looked at the nurse for a while, then he said, "Nobody has ever let me choose that before. Are you really going to let me choose now?"

    "Yes, Mr Green," the nurse answered. She was in a hurry, "Where do you want it?"

    "Well, then,'' the old man answered with a smile, "l want it in your left arm, please."

1938年3月底到4月初，他们（日军）遇到了中国军队的英勇抵抗，双方伤亡达三万人之众。这是自南京沦陷后中国方面的第一个大捷。”这次大捷发生在（ ）

把一个凸透镜正对着太阳光，在距凸透镜15cm处得到一个最小最亮的光斑。将点燃的蜡烛放在离凸透镜14cm处，经凸透镜所成的像是（  ）