观察过蜗牛之后，认识其家是个螺旋状的壳，然后以简单线条画出大小不同的蜗牛。

Observe the snail and their special 'home'. Then use simple lines to draw some snails.

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今天的这个是我在英国南部威尔特郡的白垩山丘捡到的一个深蓝色的蜗牛壳，上面有呈螺旋状的，淡青色和紫色交叠着的花纹。

Today's is a dark blue snail-shell, spiralled and chequered with paler blue and purple, picked up somewhere on the Downs.

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