一道英语填空题.要用所给单词的正确形式填出来
下面的这段话,要用下面给出的单词填空（正确形式）
[improve,plant,grow,cut down,pay more attention to,knock ,stop,try,be,experience]
The environment inthe north of China(1)--------greatly since the government took measures to plant more trees.Beijing(2)---------(not) as many sandstorms as ie used to.There(3)-------three sandstorms in Beijing since the beginning of this year.This is good considering that Beijing experienced more than a dozen sandstorms a year during the 1990s.The Chinese goverment and the Chinese people(4)------the environment now.Many trees(5)-------in the west and event more will be planted over the next few years.The young trees(6)------guickly.These trees(7)-----the soil from being carried away by strong winds.Unhealthy trees(8)-----from time to time.The villagers in the west have been highly involved in the project.They plant trees,water them,and make sure their cows(9)-----(not)them down or eat them.They(10)-----their best to protect the trees.It is hard work but they know it is worth it.