镍铬合金基底冠铸造后，在烤瓷前可进行的处理，除了（） A.磨改外形 B.试冠 C.喷

     Some animals can be trained to help humans. For example, specially trained dogs help blind

people walk around the town safely. Some kinds of monkeys can be taught things too. They can

learn how to help people who can't use their arms or legs. The monkeys pick up the phone when

it rings, carry shopping bags and do housework.

     In the wild, animals and humans are not usually friends, but there are a few interesting examples

where they can work together. In Africa, the honeyguide bird works with humans to find food. The

bird likes to eat the grubs (幼虫) - a type of insect that lives inside a beehive (蜂巢,蜂窝). It knows

how to find beehives but it can't open them and get the grubs. People like to eat honey, but they

aren't very good at finding beehives, so the bird and the people help each other. The bird flies to a

beehive and people follow it. When the people open the beehive and take the honey, they give the

grubs to the bird.

     In Laguna in the south of Brazil, fishermen and dolphins work as a team. The ocean isn't very

clean, so the fishermen can't see the fish. However, dolphins can find them easily by using sounds.

When the dolphins find a large group of fish, they make a noise to tell the fishermen. Then the

dolphins push the fish to the beach. The fishermen wait in the water near the beach and catch a lot

of fish in their nets. The fishermen's nets make it easier for the dolphins to catch fish too. In Laguna,

fishermen and dolphins have been working together for many years. The fishermen teach their

children how to work with the dolphins. The dolphins must be happy to help because they teach

their babies how to work with the humans!

1.How do some dogs help people?

 A. They help people who can't walk.

B. They help people who can't see.

C. They help people who can't hear.

D. They help people who can't carry things.

2. Honeyguide birds help people______.

A. find grubs B. find honey C. open beehives D. make honey

3. How do dolphins help fishermen?

A. They make sounds to send the fish away.

B. They make sounds and then eat the fish.

C. They make sounds and then push the fish to the beach.

D. They make sounds to make the fish jump into the nets.

4. What is the main idea of this article?

A. Animals are our friends.

B. Some animals can help people.

C. Animals are born to help people.

D. Any kind of animals can work with humans.

热力管道的平面布置主要有( )。

A．枝状

B．环状

C．带状

D．点状

（16分）如图所示，水平光滑地面上停放着一辆小车，左侧靠在竖直墙壁上，小车的四分之一圆弧轨道AB是光滑的，在最低点B与水平轨道BC相切，BC的长度是圆弧半径的10倍，整个轨道处于同一竖直平面内。可视为质点的物块从A点正上方某处无初速下落，恰好落人小车圆弧轨道滑动，然后沿水平轨道滑行至轨道末端C处恰好没有滑出。已知物块到达圆弧轨道最低点B时对轨道的压力是物块重力的9倍，小车的质量是物块的3倍，不考虑空气阻力和物块落人圆弧轨道时的能量损失。求

（1）物块开始下落的位置距水平轨道BC的竖直高度是圆弧半径的几倍；

（2）物块与水平轨道BC间的动摩擦因数μ。

以下（）不是水利水电工程管理体制改革的主要目标。

A.建立职能清晰、权责明确的管理体制

B.建立专业化和社会化的维修养护体系

C.建立定期的水价调整机制和收费体系

D.建立健全较为完善的政策法律支撑体系

反“客里空”是怎么回事？