渠道管理者可能会选择多于一个的渠道结构是为了（） A.减少产品分销的成本 B.最大化

下列说法正确的是[ ]

A、由化学元素组成的单质或化合物就是矿物

B、矿物是岩石圈物质最基本的组成单元

C、花岗岩是由石英、云母、方解石等集合而成

D、地壳本身的物质在不断循环和转化的同时，与其外界不进行物质的循环和交换

（６分）某化学小组同学利用下图所示装置进行实验。

（1）A处放碳酸钠固体，B处放适量石蕊溶液，用注射器注入少量稀盐酸，同时打开K。一段时间

后，观察到B处的现象是　。说明产生此现象的原因是（用化学方程式表示）。

（2）A处放二氧化锰，B处放木炭，C中放澄清石灰水。为验

证可燃物燃烧的两个条件，进行了如下实验：

①打开Ｋ，用注射器注入一定量氮气，　　　　（填操作方法），

木炭不燃烧，此操作目的是　　　　　。

②一段时间后，用注射器注入足量的过氧化氢溶液，同时打开K，A处产生气体，木炭不燃烧，澄清石灰水未变浑浊。Ａ处反应的化学方程式为　　　　　　　。

　　　③在B处点燃酒精灯，观察到木炭燃烧，发白光，澄清石灰水变浑浊，Ｃ处发生反应的化学方　　　　程式为                            。

阅读理解。

     Most rain forests lie close to the equator (赤道), where the climate is often mild and there are long hours

of sunshine. The warmth of the land heats the air above, causing it to rise and tiny drops of water to fall as

rain. The rainfall can reach at least 98 inches a year. This wet, warm world with plenty of sunlight is perfect

for plants to grow, so the trees grow fast with green leaves all the year round. The trees themselves also hare

an effect on the climate. They gather water from the soil and pass it out into the air through their leaves. The

wet air then forms clouds, which hang over the treetops like smoke. These clouds protect the forest from the

daytime heat and night-time cold of nearby deserts, keep temperatures fit for plant growth.

     Rain forests slightly farther away from the equator remain just as warm, but they have a dry season of three

months or more when little rain falls, Tree leaves fall dining this dry season and new leaves grow when the wet

season or monsoon (雨季) begins Thus these areas are known as the "monsoon forest".

     Another type of rain forest grows on tropical mountains. It is often called the "cloud forest" because clouds

often hang over the trees like fog.

     The rain forest is the ideal place for the growth of many different trees. Most of them depend on animals to

eat their fruits and spread their seeds. When the fruits are eaten, the seeds inside them go undamaged through

animals, stomachs and are passed out in their droppings. The seeds lying on the forest floor then grow into

new trees.

1. The climate of the rain forests near the equator is _____.

A. mild, wet and windy

B. hot, rainy and foggy

C. hot, wet and cloudy

D. warm, wet and sunny

2. We can learn from the passage that _____.

A. tree leaves are green all the time in the monsoon forest

B. there is a dry season in the cloud forest on tropical mountains

C. clouds help the plants in the rain forest near the deserts to grow

D. the formation of climate in the rain forest has little to do with the trees

3. According to the passage _____ play the most important role in the spreading of seeds.

A. animals

B. droppings

C. fruits

D. winds

4. This passage is most likely to be found in _____.

A. a travel guide

B. a story book

C. a technical report

D. a geography book

CT扫描常见的伪影有（）

A.月牙状伪影

B.卷褶伪影

C.中心线伪影

D.放射状伪影

E.以上全是

使用灭火器时，应注意以下哪几点（）

①站在上风方向灭火

②站在下风方向灭火

③对准燃烧点根部喷射

④对准燃烧点上部喷射

A.①③

B.②④

C.①②③

D.①②③④