Changes in our lives (生活) are everywhere
In the past, people wrote to each other. They had to spend (花费)a lot of time waiting for the letters. .But now we can contact (联系) each other by phone and computer.
In the past, we went to markets and shops to buy things. But now we like to buy things online. We can buy things at any time if we want to.
In the past, the teaching tools (工具) were only chalks (粉笔) and blackboards. But now teachers use computers to teach students. Computers make study more colourful and interesting. Students can also do homework online.
1.People spent lots of time waiting for the letters in the past.2.Now, we can buy things at any time in the markets.
3.We can contact each other by phone and computer before.
4.Now, the teaching tools are only computers.
5.Students can use computers do their homework now.
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