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Wood has many uses. It is a very important kind of building material. Wood can be made into desks, chairs, beds and many other things. Paper is made from wood too.
Only trees can provide enough wood. Trees can provide us with oxygen (氧气) and make the air fresh. In hot summer, trees give us shade (阴凉处；树荫) and make our surroundings more beautiful. What’s more, trees can stop soil (土壤) from being washed away by heavy rain. Since trees are so important to us, we should plant more trees. At the same time, many effective measures (有效措施) should be taken to protect forests and prevent trees from being cut down.
1．Wood is a kind of building material. （2．Only trees can provide wood. （
3．Trees can stop soil from being washed away by heavy rain. （
4．Wood is more important than trees. （
5．We don’t need to plant more trees. （
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
