资料一：文献表明1体积水要完全溶解1体积二氧化碳，至少需要约7天的时间。如果是1天时间，则1体积水大约只能溶解 $\frac{1}{3}$ 体积的二氧化碳。

资料二：对任何气体的收集，凡能用排水法收集的气体，最好用排水法收集，这样既可以观察集气的快慢，又可以提高被收集气体的纯度。

资料三：二氧化碳不溶于饱和的碳酸氢钠溶液。

我国的地形复杂多样、山区面积广大，尤其是纵横交错的山脉，构成了地形的骨架，高原、平原、盆地和丘陵镶嵌其间。读下面四组山脉图，完成题。

图中数字，表示青藏高原的是（   ）

完形填空

  It was very hot in the middle of summer and there were no trees 1the street. Mr. Read 2 his shop at half past five, and went 3 into the street and began walking to the bus stop. He was very 4. The sun shone straight down the street, and in a few minutes Mr. Read5very hot.

     A small boycame out of another6 in the street and 7Mr. Read. He stayed very8 him all the time, and he kicked Mr. Read's 9several times. Mr. Read looked at him 10 each time.

     After thefourth time, Mr. Read stopped, turned 11 and said to the small boy, "What are you doing? 12 following me like that! You're going to 13 my feet."

     "I'm 14, but don't stop me, please!" The small boy said, "It's very hot today, and there isn't 15shade anywhere else in the street."