各种物质间存在着某种联系：用A代替“大于”，B代替“小于”，C代替“等于”，D代替“无法判断”，请分别选用“A”、“B”、“C”或“D”填空．

（1）沸点：在同温同压下，氧气　____ 　氮气；

（2）微粒直径大小：分子　____ 　原子；

（3）50mL酒精与150mL水充分混合：溶液的体积　____ 　200mL．

（4）碳元素的质量分数：甲醛（CH₂O）　____ 醋酸（C₂H₄O₂）．

看地图，面对地图，通常是（　　）

如果$\left\{\begin{array}{c}x=a\\ y=b\end{array}\right.$是方程x﹣3y=﹣3的一组解，那么代数式5﹣a+3b的值是（　　）

   A pretty, well-dressed young lady stopped a taxi in a big square, and said to the driver, “Can you see that young man at the other side of the square?”
   “Yes,” said the taxi-driver. The young man was standing outside a restaurant and looking impatiently at his watch every few seconds.
   “Take me over there.” said the young lady.
   There were a lot of cars and buses and trucks in the square, so the taxi- driver asked, “Are you afraid to cross the street.”
   ‘Oh, no !” said the young lady. “But I said that I would meet that young man for dinner at one o’c1ock, and it is now a quarter to two. If I arrive in a taxi, it will at least seem as if I have tried not to be too late.”

对下侧图表理解正确的有（      ）

①长春市民营经济纳税额逐年提高                   ②民营经济是社会主义经济制度的基础
③民营经济是我国社会主义市场经济的主体   ④民营经济是我国社会主义市场经济的重要组成部分