Have you ever spent an afternoon in the backyard, maybe grilling or enjoying a basketball game, when suddenly you notice that everything goes quiet? There is an old phrase “calm before the storm”， often used in a situation—a quiet period just before a great activity or excitement. According to our own experience, we know there is actually calm before the storm. But what causes this calm? And is it always calm before the storm? Let's hear what scientists have to say.
A period of calm happens in a particular kind of storm, the simplest kind of storm—a single－cell thunderstorm. In this type of thunderstorm, there is usually only one main updraft, which is warm, damp air and drawn from places near the ground. Storms need warm and damp air as fuel, so they typically draw that air in from surrounding environment. Storms can draw in the air that fit their need from all directions—even from the direction in which the storm is traveling.
As the warm, damp air is pulled into a storm system, it leaves a low－pressure vacuum(真空) coming after. The rising air meets the cold dry air that has already existed in the storm clouds, thus the temperature of the warm, damp air drops, and the water vapour(水蒸汽) in it changes into tiny drops that are a precondition of rain. These drops accumulate and build on larger particles like dust, until they grow large enough to form raindrops.
This warm, damp air keeps moving upwards, but it becomes cooler and drier during its trip through cloud. When it reaches the top of the cloud, the air gets spit out(被挤出) at the top. This air is sent rolling out over the big thunderclouds. From there, the air goes down. Warm and dry air is relatively stable, and once it covers a region, that air, in turn, causes the calm before a storm.
Most thunderstorms, though, don't start with calm. That's because most are actually groups of storms with complex wind patterns. There's so much air moving up and down storm groups that the calm before the storm never happens. Instead, before the storm, it might be really windy!
1.Which best fits the description of a particular kind of storm?
A. A storm with air drawn from every direction.
B. A thunderstorm without strong winds.
C. A thunderstorm with a single shape.
D. A storm fueled by moving air from the ground.
2.What does the underlined word “it” in Paragraph 3 refer to?
A. Cold and dry air. B. Warm and damp air.
C. Cold and damp air. D. Warm and dry air.
3.Which does the writer most likely agree to?
A. Presence of the calm relies on stable air.
B. Storm happens without air moving up and down.
C. The drier the air is, the bigger the storm will be.
D. Not all thunderstorms start with the calm.
4.What is the passage mainly about?
A. Causes and effects of a heavy storm.
B. An explanation of the calm before a storm.
C. A personal experience of a heavy storm.
D. A brief description of a peaceful storm.
The hemlock(铁杉) trees along the Wappinger Creek, New York, look healthy. However, scientist Gary Lovett says the white balls which provide protection for the bugs are created by a tiny insect. It’s hard to believe the tiny bug could kill a tree. However, trees can end up with millions and millions of the pests. When there are that many, it ends up killing the tree.
The bug from East Asia is slowly killing trees across the USA. The trouble－making bug is just one of many invasive(入侵的) pests that have slipped into the United States. They can hurt other living things in their new home.
Many invasive pests arrive on wooden pallets piled inside shipping containers. They support and separate goods, and keep them from sliding around. Invasive pests often tunnel into the pallets. How can we stop pests from riding on pallets? Lovett says new rules are needed. The companies that make pallets don’t want more rules. Congress has added an amendment(修正案) in the 2018 Farm Bill to try and prevent this problem. However, Lovett is not hopeful it will make much of a difference. Pallets are checked by inspectors. Many are sprayed with bug－killing pesticide. “I believe in the system，” said Brent McClendon, president of The National Wooden Pallet and Container Association. He also said shipping containers are checked very carefully.
Still, each year 13 million containers are shipped to the U.S. Each is full of wooden pallets. Lovett says: “Inspectors can’t possibly check everything. All it takes are a few bad pallets; we should get rid of wooden pallets.” He believes pallets should be made of plastic or eco－composite wood. Eco－composite wood is a mix of wood fiber and plastic. Insects cannot hide into it. One problem is that these choices cost more. They may be worth the extra money, though. Invasive pests cost the U.S. $5 billion a year. Trees don’t just die in forests. They also die in cities and our yards. Then, they need to be replaced. That costs money, too.
1.All the statements are TRUE except that ________.
A. pesticide has been applied to bug－killing
B. the companies making pallets don’t want more rules
C. invasive pests hide in pallets used in shipping
D. invasive pests are native to Wappinger Creek
2.What can we infer from the passage?
A. Bugs won’t bother the tree if just in few numbers.
B. Bugs ruin the shipping goods slowly.
C. Bugs can be easily spotted by eyes.
D. Bugs cover trees with white soft balls for protection.
3.Why does Gary Lovett want to get rid of wooden pallets?
A. Because insects mostly die in them.
B. Because they are the major pest carriers.
C. Because they are not worth extra money.
D. Because plastic pallets are eco－friendly.
4.What does the passage mainly talk about?
A. Congress contributes a lot to dealing with invasive pests.
B. Effective measures have stopped the pest invasion.
C. Invasive pests are harming plants in the USA.
D. Ecosystem in the USA is poorly damaged by invasive woods.
While staring out of the window during a flight, not everyone will think carefully about the question why airplanes have rounded windows rather than square ones.
Over the years, aerospace engineering has made huge steps in airplane technology, meaning planes can carry more passengers and go faster. The planes have also changed shape to increase safety—including the windows. As commercial air travel took off in the mid－20th century, airline companies began to fly at higher altitudes to lower their cost—the air density(密度) is lower up there, creating less drag(阻力)for airplanes. However, higher altitudes came with problems, like the fact human beings can’t really survive at 30，000 feet. To make that possible, the cabin was changed to a cylindrical(圆柱体) shape to support the pressure inside. But at first, plane builders left in the standard square windows and this expansion meant disaster. The de__Havilland__Comet came into fashion in the 1950s. With a closed cabin, it was able to go higher and faster than other aircraft.
However, where there’s a corner, there’s a weak spot. Windows, having four corners, have four potential weak spots, making them likely to crash under stress—such as air pressure. By curving the window, the stress that would eventually break the window corner is distributed and the chance of it breaking is reduced. Rounded shapes are also stronger and resist deformation(变形), and can thus survive the extreme differences in pressure between the inside and outside of the aircraft.
Fortunately, designers figured out the lack of design pretty quick. Now we have nice, rounded airplane windows that can resist the pressure of traveling altitude. It gives being able to gaze out of your window to the world from 35，000 feet a whole new outlook, doesn’t it?
1.Why did airlines aim to fly at higher altitudes?
A. To increase safety of the plane.
B. To help the plane to take off.
C. To save money for less drag.
D. To carry more passengers and go faster.
2.What does the underlined words “de Havilland Comet” in Paragraph 2 refer to?
A. A planet. B. A band. C. An aircraft. D. A design.
3.Which is the advantage of the rounded window?
A. It reduces the possibility of breaking up.
B. It weakens the strength of air pressure.
C. It increases the air pressure.
D. It helps to survive the extreme weather.
4.Where does this text come from?
A. A newspaper on safe driving. B. A magazine on fashion design.
C. A website on survival skills. D. A science book on flying.
WHO’S WHO IN THE ZOO?
Is it amazing that the WHO’S WHO IN THE ZOO makes it fun for young children to save? With the help of Standard Bank’s Kidz APP and the Big Five animal friends, teaching your children about managing their cash has never been more fun. Let the WHO’S WHO IN THE ZOO show your little ones what it means to earn and save money as well as share in the enjoyment of spending their well－earned cash.
Elephant
As your children use the mobile app to complete various actions—achieving savings goals, completing missions and achieving wishes—here various medals will be rewarded.
Earned medals are displayed in the elephant habitat as well as locked medals still to be achieved.
Leopard
Reward your kids with pocket money for completing ‘missions’: household chores, achievements, etc.
You can create a mission for your child, or your child can request a new mission. Once created, it must be accepted. The mission needs to be completed by your child and approved by you before you can pay him or her.
Lion
Help your children create and fulfil wishes. Wish cards and their savings progress can be tracked from your banking app.
Once their savings goal is reached, lion will inform you of their achievement.
Buffalo
Kidz can request to withdraw cash or purchase airtime and data using their savings.
Rhino
Rhino shows your child’s latest account balance and transactions.
Download the Standard Bank’s Kidz APP from Apple App Store on the phone. Use the comment section to interact with other Standard Bank customers and bank consultants.
1.What is the WHO’S WHO IN THE ZOO designed for?
A. Players of board games. B. Kids for self－service banking.
C. Parents for online banking. D. Travelers in the zoo.
2.Rewards will be paid if ________.
A. the kids fulfil your created missions
B. your kids get enough locked medals
C. you keep the account balanced
D. you approve the request via Kidz APP
3.Which of the following animals is related to spending?
A. Rhino. B. Leopard. C. Lion. D. Buffalo.
听下面一段独白，回答以下小题。
1.Where did the shark attacks occur recently?
A. In California. B. In North Carolina. C. In Florida.
2.Who is Graham Schwartz?
A. A shark expert from a university.
B. A researcher from a museum.
C. A writer for a magazine.
3.What can people do to avoid being attacked?
A. Avoid wearing certain types of bathing suits.
B. Make their presence known in the water.
C. Only swim where the water is warm.
4.What did the Department of Parks and Recreation do?
A. They conducted a study on shark attacks.
B. They closed down the beaches.
C. They forced boats and fishermen to stop all activities.
听下面一段较长对话，回答以下小题。
1.How does the woman know about eye problems?
A. From a friend. B. From an article. C. From a TV program.
2.How often do people blink while staring at the computer screen?
A. 7 times per minute. B. 22 times per minute. C. 27 times per minute.
3.What does the woman think the man should do?
A. Avoid using computers. B. Close eyes often. C. Take a break and rest.
4.What are the speakers going to do next?
A. Keep on reading. B. Go to a drug store. C. Have some tea.
