2 .

Everyone tries to get to school on time. But when bad weather gives you trouble, can you still make it before the bell rings?

In northern China during spring, big sandstorms (沙尘暴) often make trouble for students and everyone else. When the sky is dark with sand (沙子), buses and cars all move much more slowly. Sometimes, people can’t even see for 20 meters. Sandstorms usually happen in spring. They have happened in more than 10 provinces in northern China this year.

People in southern China don’t have to worry about this kind of bad weather. Most of the sand comes from Gansu and Inner Mongolia (内蒙古). In northern China, lots of places have few trees and don’t get much rain. People there have been cutting down too many trees. When there aren’t many trees, the ground can’t keep enough water. Over the years, the ground dries up and turns to sand. When spring comes and the ice melts (融化), the ground becomes looser (更松散的). Strong winds take the loose sand into the sky.

Sandstorms are bad for people’s health. If people breathe too much sand, they could cough or have asthma (哮喘). Sandstorms also give farmers lots of problems. Sometimes their sheep get lost in the storms and never get back home. The winds also tear down farmers’ houses.

To stop sandstorms, you can ask your parents to help you plant some trees this spring. If you see people cutting down too many trees, tell them about the dangers of sandstorms, and ask your government to stop them from cutting.

7 . Everyone tries to get to school on time. But when bad weather gives you trouble, can you still make it before the bell rings?

In northern China during spring, big sandstorms (沙尘暴)often make trouble for students and everyone else. When the sky is dark with sand, buses and cars all move much more slowly. Sometimes, people can’t even see for 20 metres.

Sandstorms usually happen in spring. This year, sandstorms started in late March. They have happened in more than 10 provinces in northern China this year. More than 70 million people have had problems in those places because of the sandstorms.

People in southern China don’t have to worry about this kind of bad weather. Most of the sand comes from Gansu and Inner Mongolia（内蒙古）. In northern China, lots of places have few trees and don’t get much rain. People there have been cutting down too many trees. When there aren’t many trees, the ground can’t keep enough water. Over the years, the ground dries up and turns to sand. When spring comes and the ice melts（融化）, the ground becomes looser（更松散的）. Strong winds take the loose sand into the sky.

Sandstorms are bad for people’s health. If people breathe（呼吸）too much sand, they could cough or have asthma（哮喘）.

Sandstorms also give farmers lots of problems. Sometimes their sheep get lost in the storms and never get back home. The winds alsotear downfarmers’ houses.

What can you do to stop sandstorms? Here’s an idea: Ask your parents to help you plant some trees this spring.

If you see people cutting down too many trees, tell them about the dangers of sandstorms, and ask your government to stop them from cutting.

Do you know what makes lightning（闪电）?Why does lightning strike（击打）?

Lightning strikes happen when ice and water in clouds rub（摩擦）together, and cause atmospheric（大气层的）changes. When this happens, it creates a static charge（静电）．Lightning can strike inside the cloud, between two clouds or between a cloud and Earth. It’s the last kind of strike that is the most dangerous for humans.

Lightning can be very dangerous. Every year, lightning kills people because it can start big fires or because it reaches a temperature of 28, 000 ℃. About 1, 000 people are hit by lightning every year in the United States, and about 100 of them die as a result.

Lightning makes people shocked, and it happens all over the world! Scientists think that there are more than three million lightning strikes every day in the world—that’s thirty strikes every second（秒）. An American man Roy Sullivan, who worked in a park, survived from the most lightning strikes. Between 1942 and 1983, he was hit seven times! And he keeps the highest world record.

Lightning is sure not something to play with. When lightning strikes, it’s best to stay inside a large building. To stay safe, do not stand under trees, on hills or near water. Also, do not lie down on the ground, or the electricity may go through you and cause a heart problem.

9 . Oct 29, 2012 was a dark day for the American people. A huge hurricane (飓风) named Sandy hit the US, along with thunderstorms, heavy snow and flooding. It caused great damage in many places. Cities like New York were left with flooded streets and no electricity.

A hurricane is a kind of tropical cyclone (热带气旋) that is found in the northeastern Pacific Ocean, South Pacific, or North Atlantic Ocean. When it appears in the northwestern Pacific, it is called a typhoon. Southern China has the longest record of experiencing typhoons in the area.

So hurricanes and typhoons are the same thing; the only difference is where they happen. They form on the sea and are caused by temperature differences.

There is another kind of cyclone called a tornado. A tornado forms from the twisting (扭曲) of rising air. It's a violently rotating (旋转的) column of air that connects with clouds above it and the land below.

Tornados form on the land and often begin with thunderstorms. The US has the most tornados of any country. This is because of some of the special features of the North American continent. The continent spreads from the tropical north to the arctic (北极的). There are no large mountains from east to west, so it is easy for warm and cold air to meet. When this happens, thunderstorms soon follow.

As for Hurricane Sandy, scientists believe that it began due to unusually warm water. Then it joined with a large Arctic weather system, which increased its size and changed it into a winter storm with far more power.

10 . Earthquakes usually come without warning. What should you do if this happens to you? An earthquake is dangerous, but there are still things you can do to protect yourself.

Stay calm as the earth begins to shake. Your chances of survival in an earthquake go up if you can keep calm. Staying calm is not easy, but it can save your life.

If you are inside when the earthquake starts, get under a table or a bed. You need to have something strong around you to protect you from falling objects. Do not stand near walls and windows and stay out of the kitchen. The kitchen is dangerous because of many glass objects.

If you are outside, get to an open area as fast as you can. Stay away from buildings and trees. If you are in a car, pull over to a place where there are no trees or tall buildings and stay in the car. If you are close to the sea, try to get as far away from the water as possible. Earthquakes can cause huge waves(浪) that can really harm the people nearby.

When the earthquake is over, there is still plenty of danger. For example, gas fire often comes with an earthquake. If you see a fire, quickly move outdoors to an open area.

Always remember to hope for the best but prepare for the worst.