There used to be no electric lights, only dim oil lamps. Edison's invention is inconvenient under the dim oil lamp at night. So he thought: Why not invent a simple and bright lamp? After coming up with this idea, he constantly overcame "difficulties" and finally met with "nails" when choosing a filament. After testing more than 1000 kinds of filament, he found that platinum filament had the best test effect, while incandescent filament was expensive and could not be widely used. "There are many good things to grind." After replacing more than 2000 kinds of filament, he installed the world's first practical electric lamp with cheap carbon filament.
It was the Curies who discovered the radioactive element radium, but their most outstanding achievement was their persistent extraction of radium. At that time, in order to prove the existence of radium, the Curies finally got a ton of industrial waste residue that might contain radium. They set up a cauldron in the borrowed shed, and they kept melting it, and then dissolved, precipitated and analyzed the melted part. All day long, in the smoky fire of the shed, they tirelessly stirred and analyzed the slag with the pain of acid and alkali burning. "There are many good things to grind." Three years and nine months later, the Curies extracted 0. 1 gram of radium.
"Many good things grind", as long as you make unremitting efforts, you will reap success.
Grade 6 of Sancao Primary School in Bozhou, Anhui Province: Ma Yiming