The doctors said that ( ) do little to keep the virus out.
A. surgical mask
B. cold-weather mask
C. gas mask
D. anti-pollution mask
lots of people purchased and mailed ( ) from overseas.
A.the anti-pollution masks
B. the gas masks
C. the surgical masks
D. the cold-weather masks
人们口中提及的“N95”实际指的是以下哪种口罩?
A. the surgical mask
B. the cold-weather mask
C. the gas mask
D. the anti-pollution mask