据资料统计：在明后期至清前期200余年间，世界白银产量的一半流入中国，拥有一流城市和最为密集、完善的市场网络的中国，成为当时世界经济和贸易的中心区域。然而当时它却没有形成强大的扫荡旧经济基础的革命性变化。对材料中“没有形成强大的扫荡旧经济基础的革命性变化”的准确理解是（  ）

在分子、原子、质子、中子、电子中，找出符合下列条件的粒子名称，填在相应的横线上．

（1）能直接构成纯净物的粒子是____ ．（2）能保持物质化学性质的粒子是____ ．

（3）化学变化中的最小粒子是____ （4）带正电荷的粒子是____ ．

（5）带负电荷的粒子是____ ．（6）不显电性的粒子是____ ．

（7）决定原子质量大小的粒子是____ ．（8）在同一原子中数目相等的粒子是____ ．

阅读理解
   There is an old English saying.It tells us that we must go to bed early and get up early in the morning.Then we shall be healthy.We shall also be rich and clever.This is true.The body must have enough sleep to be healthy.Children of young age should have ten hours' sleep every night.Children who do not have enough sleep cannot do their work well and they may not be healthy.The body also needs exercise.Walking, running, jumping and playing games are all exercise.Exercise keeps the body strong.Exercise also helps the blood to move around inside the body.It is very important.Our blood moves to all parts of our body.The head also needs blood.Exercise helps us to think better.