题目内容
The air is so______ that the smoke is rising straight up.
A.calm B.silent
C.still D.quiet
C
解析:
考查意义相近的形容词辨析。still表示没有动作，silent强调 声音， calm 表示内心平静、镇静，quiet强调周围环境的安静。
名校课堂系列答案As a result of the fog haze weather, nowadays many people are longing to live ______ the air is fresher.
| A．that | B．when | C．where | D．in which |
On a hill 600 feet above the surrounding land, we watch the lines of rain move across the scene, the moon rise over the hills, and the stars appear in the sky. The views invite a long look from a comfortable chair in front of the wooden house.
Every window in our wooden house has a view, and the forest and lakes seldom look the same as the hour before. Each look reminds us where we are.
There is space for our three boys to play outside, to shoot arrows, collect tree seeds, build earth houses and climb trees.
Our kids have learned the names of the trees, and with the names have come familiarity and appreciation. As they tell all who show even a passing interest, maple（枫树）makes the best fighting sticks and white pines are the best climbing trees.
The air is clean and fresh. The water from the well has a pleasant taste, and it is perhaps the healthiest water our kids will ever drink. Though they have one glass a day of juice and the rest is water, they never say anything against that.
The seasons change just outside the door. We watch the maples turn every shade of yellow and red in the fall and note the poplars’（杨树）putting out the first green leaves of spring. The rainbow smelt fills the local steam as the ice gradually disappears, and the wood frogs start to sing in pools after being frozen for the winter. A family of birds rules our skies and flies over the lake.
【小题1】What can be learned from Paragraph 2?
| A．The scenes are colorful and changeable. |
| B．There are many windows in the wooden house. |
| C．The views remind us that we are in a wooden house. |
| D．The lakes outside the windows are quite different in color. |
| A．the kids like playing in trees |
| B．the kids are very familiar with trees |
| C．the kids have learned much knowledge |
| D．the kids find trees useful learning tools |
| A．The change of seasons is easily felt. |
| B．The seasons make the scenes change. |
| C．The weather often changes in the forest. |
| D．The door is a good position to enjoy changing seasons. |
| A．To describe the beauty of the scene around the house. |
| B．To introduce her children’s happy life in the forest. |
| C．To show that living in the forest is healthful. |
| D．To share the joy of living in the nature. |
For years, the automobile industry has been testing vehicles that use hydrogen as fuel. Now, people across the United States have had a chance to see and even drive cars that get power from hydrogen fuel cells (燃料电池).
But the hydrogen fuel cell is not a new idea. The fuel cell was first invented by Sir William Grove of Britain in 1839. Since then, many different designs, have been invented. There is one place where fuel cells are a proven technology: in space. The American space agency used fuel cells in its Apollo spaceships in the twentieth century.
The most useful fuel cell for transportation purposes is the Polymer Electrolyte Membrane, or P.E.M. fuel cell. It is simple and can operate at temperatures of sixty to eighty degrees Celsius. That is much lower than other fuel cell designs. A P.E.M. fuel cell has two sides divided by a thin membrane (膜). Hydrogen gas is forced through one side where it comes in contact with a reactive material containing the metal platinum(铂). The membrane separates the electrons(电子) from the protons(质子) in the hydrogen atoms. The protons pass through it to the other side of the fuel cell. But the electrons are captured to do work; like powering a motor. Oxygen from the air is forced into the other side of the fuel cell. There, the gas meets the protons that have passed through the membrane. They combine to form water and heat. A single fuel cell does not produce a lot of electricity. But when many fuel cells are combined, they can produce enough electricity to power a vehicle. The product of the chemical reaction that powers fuel cells is water. This makes fuel cells a very clean technology.
Hydrogen fuel cell cars have been slow to develop because of many technical problems that have to be solved. For example, it is unclear how long the membranes in P.E.M. fuel cells will last. Also, fuel cells need water for their chemical reactions. They must be designed to start easily at low temperatures and in dry climates. And smaller, less costly fuel cells must be designed before they can truly take the place of gasoline engines. Now more models of fuel cell vehicles are being tested than ever before. The threat of climate change and the high cost of oil have increased interest in these vehicles that do not cause pollution.
|
Title |
More Models of Hydrogen Cars Being Tested |
|
The progress of hydrogen fuel cell |
·(1) ________ by Sir William Grove in 1839. ·Designed (2) ________ ever since. ·Used in Apollo spaceships in the twentieth century. |
|
Operating principle of P.E.M. |
·It has two sides divided by a thin membrane. ·Hydrogen gas from one side (3) ________ the active metal platinum. ·The electrons are (4) ________ from the protons in the hydrogen atoms. ·The protons pass through the fuel cell to the other side. ·Oxygen from the air is (5) ________ into the other side of the fuel cell. ·The gas meets the protons，and then water and heat are(6) ________ |
|
Reasons for slow (7) ________of hydrogen fuel cell cars |
·There are many technical problems (8) ________ ·The durability of the membranes in P.E.M. fuel cells is not clear. ·They have to start easily at (9)________ temperatures and in dry climates. ·They must be smaller and less costly before (10) ________ gasoline engines. |
Here’s an amazing way to get a hard-boiled egg into a bottle, even though the mouth of the boiled is smaller than the egg! What’s more, you don’t even need to touch the egg to get it to go in!
For this experiment you will need:
·a hard-boiled egg
·a glass bottle with a mouth just slightly smaller than the egg (a fruit-drink bottle works well)
·a 8-cm by 8-cm(3-inch by 3-inch)piece of newspaper
·a match
Remove the shell from the egg. Set the egg on the mouth of the bottle to see that the egg does not fit through the mouth.
Light the paper. Remove the egg from the mouth of the bottle and drop the burning paper into the bottle. Before the fire goes out, set the egg back onto the mouth of the bottle. Within a few seconds the egg will squeeze(挤) through the mouth and into the bottle.
As it entered the bottle, the egg may have broken into pieces. This happens when the diameter(直径) of the egg is more than about 0.5 cm(about 3/16 inch) larger than the diameter of the bottle’s opening.
Why does the egg slide into the bottle, even though no one is pushing it? Because the pressure of the air is pushing it. Before the burning paper is put into the bottle, the pressure of the air inside is the same as outside. The burning paper, however, heats the air inside. This causes the air inside to expand. When the egg is placed on top of the bottle, it seals(封住) the bottle. When the fire goes out, the air inside cools. As it cools, the air contracts(紧缩), and the pressure of the air inside becomes less than the pressure outside. Then, the higher outside pressure pushes the egg into the bottle!
1.The best title of this passage can be .
|
A．An interesting story |
B．The pressure of the air |
|
C．Egg in a bottle |
D．Egg, bottle and match |
2.What don’t you need in this experiment?
|
A．Eggs. |
B．Water. |
C．Bottles. |
D．Paper. |
3.Why will the egg break into pieces while entering the bottle?
|
A．Because of the burning paper. |
|
B．Because the diameter of the egg is too larger than that of the bottles opening. |
|
C．Because it is cool inside the bottle. |
|
D．Because the pressure of the air inside is larger. |
4.What is the most important to get the egg into a bottle?
|
A．A match. |
B．A fruit-drink bottle. |
C．The pressure of the air. |
D．The burning paper. |