题目内容：

Way back in 1674, a frog helped Antoni van Leeuwenhoek make an incredible discovery. Antoni was an amateur scientist from Holland, so fascinated by microscopes 1. he’d built some of his own. One rainy day, as he went for a walk, a leaping frog 2. (draw) his attention to a puddle.

Antoni collected a drop of puddle water and put it 3. his microscope. He was amazed4. (see) a whole community of creatures swimming in this one drop — tiny beings no one had ever seen before.

These tiny beings, called microbes, are everywhere: in dirt, in food and on your kitchen table. People 5. (cover) in them, too. 6. you were to count all the microbes on and inside your body, you would find your body has more microbes than the world has people — over 6 billion!

Microbes can’t survive on 7. (they) own. They need food. After 8. (settle) into a home — you, for instance — they steal vitamins and other nutrients and leave behind dead cells and poisonous liquids called toxins. Some microbes can make you sick. People usually call these ones germs. 9. (lucky) for you, there are more 10. (help) microbes, working together to keep you healthy, than bad ones.