Dear Editor , I used to be a doctor in a children's hospital. Sometimes I treated children who had been poisoned by medicines for older family members. The children didn't know the medicine was dangerous; they just knew it tasted sweet. Children easily opened the bottle that we now use in China. Some days ago I talked about medicine with an American. He showed me a kind of plastic bottle. The design was very quite simple and I'm sure our Chinese factories could produce these bottles. The top of the bottle locks but can be opened by pressing down on it while turning. This is difficult for most young children to do, though grown-ups can open these bottles very easily. I'm certain that the price of making such tops would be very low. As a doctor, I'd love to see this done. And most parents would be grateful. Yours, Li Hua The writer's job in the hospital was mainly to  _  .
treat sick children treat poisoned children give medicine to people give medicine to children