阅读表达 阅读下面的短文，根据短文内容回答问题。
Smog（雾霾）is one of the hottest subjects these years. It does great harm to people’s health. The most terrible smog lasted for about a week in February, 2014. It covered 15 percent of the land in northern and central China.
Now, more and more people in China have realized the importance of protecting the environment. They try to save energy by walking or riding to work in their daily life. Cities including Beijing and Shanghai have taken action by controlling the number of cars and closing heavily polluting factories.
Beijing is heavily polluted, so it’s not easy to see blue skies there. But during the APEC summit（亚太经合会议峰会）in November last year, Beijing saw blue skies for a few days. People happily call that “APEC blue”.
“I hope the APEC blue will last, and I believe it will, because China has put great effort into reducing pollution.” said President Xi Jinping during the summit.
The two large countries, China and the USA, produce about 45 percent of the world’s greenhouse gases（温室气体）.On November 12, President Xi Jinping and Obama announced that both countries would work together to cut down CO2 emissions（二氧化碳的排放）. The goal needs everyone’s effort.
回答下面5个问题，每题答案不超过6个词。
How long did the most terrible smog last in China in February, 2014?
How do more and more Chinese people help save energy in their daily life?
Why is it difficult for Beijing to see blue skies?
When was the APEC summit held in Beijing?
What would China and the USA work together to do?