题干
-You look so worried, what’s wrong?
-More and more people like me begin to worry about the ______ pollution after the haze (雾霾) appeared in Beijing and some other cities in China.
A：water
B：air
C：noise
D：Soil
答案(点此获取答案解析）
B
为了节省能量，某商场安装了智能化的电动扶梯。无人乘行时，扶梯运转得很慢；有人站上扶梯时，它会先慢慢加速，再匀速运转。一顾客乘扶梯上楼，恰好经历了这两个过程，如图所示。那么下列说法中正确的是（ ）