搜索
April 13th
It was April 13th, 2022. It was a special day. We could go everywhere. From March 29th to April 12th, we had to stay at home. The students studied on the Internet. But there were some special people. They had white clothes. We called them “Dabai”. They helped us all day and night. Now we can go to work, go to school and so on. We are happy. We must remember them.
1．This is a letter.2．April 13th was a special day.
3．We couldn’t go out on March 26th.
4．We must remember “Dabai”.
5．Now we can’t go everywhere.
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
