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There are three little pigs. When they grow up, they leave(离开) home to build their own houses. The first little pig builds a house of hay(草料). It is easy to make. It takes(花费) him one day to build the house. The second little pig builds a house of wood(木头). It takes him three days to build the house. The third little pig builds a house of stone(石头). It takes him three months to build the house. The stone house is strong and beautiful.
One day, a bad wolf comes. He wants to eat the pigs. He blows(吹) the hay house down. The first little pig runs to the second pig’s house. The wolf then knocks(撞) the wooden house down. The two little pigs run to the third pig’s home. The bad wolf runs after them to the stone house. He blows and knocks. But he can’t destroy the house. The three little pigs are safe(安全).
1．It is difficult to build a house of hay.2．It takes the second pig three days to build a stone house.
3．The bad wolf can’t blow the stone house down.
4．The bad wolf knocks the wooden house down first(首先).
5．The wolf wants to make friends with the three pigs.
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
