下列物质中，既有游离态氧，又有化合态氧的是（ ） A．空气 B．铁锈 C．液氧

阅读理解       

        Johnson likes swimming in a small river near his house. But then his father goes to work in a big city

and Johnson goes with his family. Their new house has a garden, but the garden is very small. Johnson is

not very happy. 

       "Is there a river near the house?" he asks his father on the first morning ." No, there isn't . But there is a big park near here. And there's a pool in it.  "We are going there this afternoon." says his father. Johnson is happy. 

       Johnson and his father go to the park in the afternoon. Johnson wants to walk near the pool. But he

sees a sign. His father reads it to him: "Warning(警告) This pool is dangerous.362 people fell(掉) into it.

"Johnson looks into the pool carefully, then he says ,"I can't see them. "

1. There is a _______ near Johnson's new house.

A. small river  

B. big park  

C. big bank  

D. big post office

2. John isn't very happy because __________.

A. There isn't a big park

B. There isn't a river near the new house.

C. his father goes to work in a big city

D. There's a pool.

3. There is a _______ near the pool.

A. sign

B. river

C. garden

D. tree

4. The warning tells people ________ near the pool.

A. to look into it

B. not to go to the park  

C. to be careful

D. not to look into it

5. Which isn't right?

A. There isn't a small river near Johnson's house.

B. Johnson's father gets a new job in a big city.

C. Johnson is afraid to walk near the pool

D. Johnson goes to the big city with his father.

阅读下列材料，回答问题．

如图所示是大自然中水循环现象的示意图．江、河、湖、海以及大地表面层中的水不断______变成水蒸气，这一过程要吸热．当含有很多水蒸气的空气升入高空时，水蒸气的温度降低______成小水滴或______成小冰晶，这就形成了云，云是水蒸气液化或______形成的，在一定条件下，云中小水滴和小冰晶越来越大，就会下落，在下落过程中，小冰晶又变成了小水滴，与原来的水滴一起落到地面，就形成了雨，小冰晶形成雨的过程属于______现象，这一过程需______热．

（1）把材料中划线部分填写完整．

（2）你也许注意过，天气预报中常说：“…向北移动的暖湿气流和来自××地区的冷空气前锋相遇，将在我国××至××之间形成一条东西方向的降雨带…”．试说明暖湿气流携带较多的水分，为什么不一定带来降雨，而与冷空气相遇才会降雨．

性格

具有翼板，能同时扩大上下牙弓的活动矫治器是（）

A．斜面导板矫治器

B．带翼扩弓活动矫治器

C．Herbst矫治器

D．螺旋器分裂基托矫治器

E．上颌双侧垫矫治器

关系操作语言是高度非过程化的，因而使关系操作具备集合操作的特点，也就是的操作方式。

A．一次二集合

B．二次一集合

C．一次一集合

D．二次二集合