搜索
You might put on a raincoat to walk in the rain, but a duck doesn’t need to. Ducks make their feathers waterproof(防水的). They spread a kind of oil over them with their beak(喙). The oil comes from a spot on their body near their tail.
You might put on a jacket to play in the snow, but a polar bear doesn’t need to. A polar bear is more likely to be too hot than too cold. Two layers(层) of fur cover every bit of the bear but its nose and the pads on the bottoms of its feet. The long, oily outer coat keeps the thick fuzzy undercoat warm and dry.
<节选改编自快乐阅读Unit 1 Who wears clothes?>
1．Ducks put on a raincoat in the rain.2．Ducks make their feathers waterproof.
3．The polar bear doesn’t need to put on a jacket in the snow.
4．A polar bear has one layer of fur.
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
