Compared with the previous week, air quality in Shanghai became worse last week , according to the latest report from the Shanghai Environment Monitoring Centre．
The average air pollution index （API） for sulphur dioxide （SO2） remain almost unchanged from the previous week, but the APIs for nitrogen oxide （NOx） and total suspended （悬浮） particles （TSP） rose by 35 and 27 percent．
The overall quality still belonged to class 2 category．Nitrogen oxide, caused mainly by vehicle exhaust and burning of cooking gas, was still the major pollutant of the week．
The Shanghai Environmental Monitoring Centre operates six automatic air monitors in the city’s Putuo, Yangpu, Luwan, Hongkou, Jing’an and Xuhui districts．
Judging from the chart, on which day was the air quality the worst?
A．October 13． B．October 14． C．October 17． D．October 18．
Which of the following can be used to describe the air quality of the week?
A．Good． B．Seriously polluted．
C．Excellent． D．Slightly polluted．
Six automatic air monitors are operated in the city except ________．
A．Putuo District
B．Xuhui District
C．Chang’an District
D．Hongkou District
In shanghai, nitrogen oxide mainly comes from ________．
A．the burning natural gas
B．the burning cooking gas
C．the burning coal
D．dust raised by vehicles
This passage is obviously taken from ________．
A．a magazine about air pollution
B．a scientific report from TV
C．the weather column in a newspaper
D．the traveling guide to Shanghai