As winter comes，we see a lot of foggy days in north China．The air is very bad for our health．
On Dec.5，China made a plan for cutting down on air pollution．According to this plan，China aims to cut the PM 2.5pollution by at least 5% by 2015in 117cities．
PM 2.5refers to pollution with small particles （颗粒） 2.5micrometers （微米） or less in diameter （直径）．The PM 2.5pollution mainly comes from human activities，especially things like motor vehicle emissions （排放）．
Health experts say that smaller particles are far more dangerous and may cause heart and lung （肺） diseases．They cannot be blocked （阻止） in our nose，and so travel directly to our lungs．
The starting point of the plan is to improve air quality（质量） and solve the PM 2.5problem．This problem directly affects （影响） many people．The final goal is to protect people's health．
To meet the five-year goal，China will promote （促进） the use of clean energy （能源） and limit （限制） the use of coal （煤） energy．Meanwhile，the country will develop its city bus and subway systems．It will also control the number of new cars．
66．What is the PM 2.5pollution？___
67．What is the biggest cause of PM 2.5pollution？___
68．Are the smaller particles in the air good for health？___
69．To solve the PM.2.5problem，what energy should we use？___
70．What is the best tile for the passage？___．