A：Y元素最高价氧化物对应水化物的化学式为：HYO3
B：X、Y、Z形成的简单离子的半径大小为：Y＞Z＞X
C：元素X、Z分别与元素W形成的化合物的沸点为：WmX＜WmZ
D：相同条件下，等物质的量浓度HnY溶液的酸性比HmZ溶液的酸性强
December 25 is Christmas Day(圣诞节). Christmas is an important holiday in many countries. On Christmas Day, most families get together for a big dinner. They give presents to each other and visit friends. The Christmas tree is an important part of the Christmas holiday. Most families buy trees. The families decorate(装饰) the tree together. Parents usually tell their children that Father Christmas comes during the night and brings presents to good children. Of course, Father Christmas isn't real. The parents of the children are really "Father Christmas". They put the presents under the tree or into their children's stocking(长统袜) after the children go to sleep.
若函数f(x)，g(x)分别是R上的奇函数、偶函数，且满足f(x)－g(x)＝ex，则有( )
请阅读下列材料，回答问题：
材料一：《史记》记载，南方地广人稀，人们以稻米、鱼为主食，还采集果实和贝类为食……刀耕火种，没有积蓄，大多很贫困。
材料二： 南宋时，民间流传着“苏湖熟，天下足”的谚语。
材料三：《宋史》中记载：“国家根本，仰给东南。”
请回答：
对于一个底边在x轴上的正三角形ABC，边长AB=2，采用斜二测画法做出其直观图，则其直观图的面积是____ ．
