Fireworks on the Field

Kaitlyn was practicing her pitching at the baseball field . She reached into her bucket for another ball . Suddenly—beep, beep, beep! A big truck backed slowly onto the field. “ Hey! ” Kaitlyn thought . “ What’s that doing here?” A man got out of the truck. “ Sorry, ” he said.

凯特琳在棒球场练习投球。 她把手伸进桶里想再拿一个球。突然，嘟嘟，嘟嘟！ 一辆大卡车缓缓后退到田野上。 ”嘿！”凯特琳想：“那在这里干什么？” 一名男子从卡车上下来。“对不起，”他说。

“ We need to set up here for tonight’s fireworks display. You’ll have to move somewhere else. ” “ The Fourth of July show is still hours away, ” Kaitlyn said . “ Can’t I practice my pitching some more?” “ I’m afraid not, ” the man said. “ It takes several hours to set up a fireworks display. ”

”我们需要在这里准备今晚的烟花表演。你得搬到别的地方去。” ”凯特琳说：“7月4日的演出还有几个小时，我不能再练习一下投球吗？” ”恐怕不行，”那人说。“燃放烟花需要几个小时。”

By now more men had arrived. They were moving wooden racks and boxes onto the field. Kaitlyn sighed. She looked closely at a rack. It held short plastic pipes. “ Those are fireworks?” “ Nope, ” the man said. “ Those are cannons that shoot the fireworks into the sky. “ He opened a box and took out a brown object wrapped in plastic.

现在已经有更多的人来了。他们正在把木架和箱子搬到田野上。 凯特琳叹了口气。她仔细看了看架子。它装有短塑料管。“那些是烟花？” ”不，”那人说。“这些是向天空发射烟花的大炮。” 他打开一个盒子，拿出一个塑料包裹的棕色物体。

It was about the size of a baseball and looked like a little bomb. “ This is a firework shell. ” “ What’s inside of it?” Kaitlyn asked. ” I’ll explain, ” said the man. He set the shell gently back into the box. Then he bent down and drew a big circle in the dirt. ” A shell is filled with little balls of gunpowder. Pyrotechnicians, like me, call these balls ‘stars. ’

它大约有一个棒球大小，看起来像一个小炸弹。“这是一枚烟花炮弹。” 里面是什么？”凯特琳问。 “我会解释的，”男人说。他轻轻地把贝壳放回盒子里。 然后他弯下腰，在土里画了一个大圆圈。 “炮弹里装满了小火药球。像我这样的烟火技师称这些球为“星星”

He picked up some baseballs and formed a pattern inside the circle with them. ” The pattern of the stars gives a firework its shape. ” ” What gives a firework its color?” Kaitlyn asked. ” Magic! ” The man laughed . Kaitlyn didn’t . She really wanted to know the answer!

他拿起一些棒球，在圆圈内形成一个图案。 “星星的图案赋予了烟花的形状。” “是什么赋予了烟花颜色？”凯特琳问。 "神奇！”男人笑了。凯特琳没有。她真的很想知道答案！

" Well, the magic of science, ” the man added quickly . " Pyrotechnicians add chemicals to the gunpowder stars . When these chemicals burn, they make different colors . Like chemicals containing copper, for example—can you guess what color they make when they burn?”

"嗯，这是科学的魔力。”男人很快补充道。 烟火技师向火药星中添加化学物质。 当这些化学物质燃烧时，会产生不同的颜色。 例如，像含铜的化学物质一样，你能猜出它们燃烧时会变成什么颜色吗？”