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The world has been troubled by COVID-19 for over a year. Masks (口罩) are really important to everybody during the pandemic (疫情). We all wear masks every day.
In a study, scientists from the US and Denmark said that people around the world are now using 129 billion face masks every month.
According to Elvis Genbo Xu from the University of Southern Denmark, disposable (一次性的) masks are plastic products.
| A．They also suggest that we use more reusable cotton masks. |
| B．Other plastic products are often recycled. |
| C．But we have to throw them away after a short time. |
| D．That is to say, we use 2.8 million masks every minute! |
| E．These used plastic masks can not only pollute the earth but also oceans. |
同类型试题
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
