If someone is lost in a forest( 森林 ), he needs only study the trees around him carefully to find his way. On this half of the earth, he will find that the side of the tree with the most leaves and branches(树枝 ) is the south side. Also, by checking the tops of the trees, he will find that they lean(倾斜 ) to the south too.
    Another sign( 标志物) for him to know where he is going is found in the bark.( 树皮) That is brighter on the south side.The remanining(树桩 ) of a cut tree is also a finder, for its rings can give him another sign. The rings will be thinner on the south side and thicker on the north side.
One more sign: some very small plants grow at the foot of a tree and they point to the north.

通过画图判断：在同一平面内，如果两条直线都和同一条直线垂直，这两条直线的位置关系是____ .

春秋战国时期出现了百家争鸣的局面，不同政治派别对各种问题提出不同的见解。在治理国家方面，道家的主张是（    ）

经过对气温的观测，我们发现一天中的最低气温一般出现在（   ）