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
查看答案
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
Which one is the most expensive mask?
A. the gas mask
B. the surgical mask
C. the silk mask
D. the gold mask
What should you do during the epidemic situation?
A. Washing your hands frequently
B. Stay indoor as you can
C. Wearing masks if you need to go out
D. Eat a lot.
力法典型方程中自由项为 ( ) 。
A. 恒为正
B. 可正可负
C. 可为零
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