【Smog（XA）isaofthehotsubjectstheseyears．Itdoesgreatharmtopeople'shealth．ThemostterriblesmoglastedforaboutaweekinFebruary，2014．Itcovered15percentofthelandinnorthernandcentralChinaNow，moreandmorepeop】

　　Smog （XA） is a of the hot subjects these years．It does great harmto people's health．The most terrible smog lasted for about a week inFebruary，2014．It covered 15percent of the land in northern and centralChina　Now，more and more people in China have realized the importance ofprotecting the environment．They ry to save energy by walking or riding to work in their dailylife．Cities including Beijing and Shanghai have taken action by controlling the number of carsand closing heavily polluting factories．

　　Beijing is heavily polluted，so it's not easy to see blue skies there．But during the APEC

　　manit（亚太经合会议峰会）in November last year，Beijing saw blue skies for a few days

　　People happily call the"APEC blue"

　　"I hope the APEC blue will last，and I believe it will，because China put great efforts intoreducing pollution．"Said President Xi hoping during the summit．

　　The two large countries，China and the USA，produce about 45percent of the world'sgreenhouse gasses（温室气体）On November 12，PresidentsXi jinping and Obama announcedthat both countries would work together to cut down COz emissions（二氧化碳的排放）．Thegoal needs everyone's effort．

　　回答下面5个问题，每题答案不超过6个词．

　　46．How long did the most terrible smog in China in February，2014？___

　　47．How do more and more Chinese people help save energy in their daily life？___

　　48．Why is difficult for Beijing to see blue skies？___

　　49．When was the APEC summit held in Beijing？___

　　50．What would China and the USA work together to do？___．