【推荐3】After finishing my teaching for a school year, I thought that I should go back to Montreal, Quebec, my hometown for a visit. My main goal was to relax in preparation for the challenges of my retirement(退休) in the coming year.

Through my stay in Montreal, I met lots of Chinese who were trying hard to succeed and then led a better life in Canada. Some travelled thousands of miles to get knowledge. When I spoke with some of them about the major barrier(障碍) they had to face after they arrived in Canada, they all talked about the two official languages of Canada. But I was impressed by their ability to express their ideas while they were changing between English and French.

Almost all of those people said they often felt homesick. They miss their families and friends. Though Montreal has lots of Chinese restaurants, they long for a home•cooked meal.

I met some tourists who were trying to realize their childhood dreams of experiencing the life in a developed country. When I asked them if Montreal had lived up to their expectations, they hesitated. They said that reality never agrees with fantasies. However, they were glad to have the opportunity to visit Montreal and didn't regret taking the trip.

Not all the Chinese people I met were happy. I once met a young lady who met with a gentleman through the Internet. However, to her disappointment, he disappeared after he promised to marry her in Montreal.

I was served by another Chinese person who could not deal with the challenges of studying in an English-speaking environment and ended up working in a restaurant with low pay.

Exploring different parts of the world, without any doubt, is an enriching experience. However, one should be realistic when it comes to leaving his hometown to start a new life in a foreign country. One should take time to examine the advantages and the shortcomings of the adventure before he decides to chase an uncertain dream of achieving success or leading a better life.

【推荐1】Human innovation (创新) has allowed people to explore space for decades. Within a space station, astronauts have enough air, food and water to complete missions of a year or longer without a resupply. But missions to further reaches of space are a different matter. Establishing a base on the moon or sending humans to Mars seems just on the horizon. That can only happen if innovative and foolproof ways are developed to supply humans with enough air, water and food.

One company, Interstellar Labs, has developed an advanced, closed loop system that can grow plants anywhere, even in space. They call their AI managed greenhouses BioPods and they are designed to be very efficient. In fact, Interstellar Labs claims that BioPods reduce the amount of land and water needed to produce food by 99 percent. That is not an impossible claim. BioPods don’t use any soil to grow plants, and the vast majority of water is recycled and recirculated.

Plants are grown inside BioPods using aeroponics, the practice of hanging plants in the air and spraying a mist of nutrient-rich water on their roots. By using aeroponics, the BioPod system carefully conserves water with amazing results. According to Interstellar labs, BioPod-grown plants are up to 300 times more productive than traditionally grown plants, using only a small amount of water.

The conditions inside of a BioPod are controlled by AI, which can change anything from the lighting to the temperature and humidity to maximize growth. This optimizes (使最优化) growing conditions no matter what the environment is outside, including the emptiness of space.

The BioPods themselves can be built in almost any environment, too. The pod’s structure is made with a 3D printer using raw materials in liquid form. The inside part is sealed with an inflatable membrane (充气膜) that is also 3D-printed. This means that a BioPod could be built right on the surface of the moon or Mars, making transporting a large structure unnecessary.

Like most technology developed for space exploration, BioPods can also be used on Earth to provide highly efficient food production systems even in the harshest environments.

【推荐2】The surface of Mars is etched (蚀刻) with ancient river valleys and lake basins. Some researchers think that liquid water once flowed on the Red Planet. Today, Mars is too cold for much, if any, liquid water to exist. And 3.8 billion years ago, when the flowing water formed, the sun was fainter than it is today, making it even harder to imagine a warm Martian climate. That’s why many researchers think Mars may have gone in and out of deep freezes.

Some researchers have suggested that early Mars only melt when large asteroid (小行星) impacts or volcanic eruptions temporarily warmed the planet. But Kasting, a geologist at Pennsylvania State University thinks warm windows from such dramatic events would have been too brief to carve the vast valleys that exist on Mars. Now, Kasting and his colleagues have come up with an alternative explanation: They think Mars may have experienced a series of climate cycles caused by changes in the strength of the greenhouse effect.

The idea goes like this: When Mars was cold and frozen volcanoes continued to erupt the greenhouse gases carbon dioxide and hydrogen into the atmosphere. There, the gas blanket trapped heat and warmed the planet up until liquid water began to flow, forming Mars rivers and lakes. However, warm temperatures and abundant water would also have sped up certain chemical reactions that consumed carbon dioxide, mitigating the greenhouse effect and cooling the planet back down again. Then the cycle would repeat.

Kasting shared his theory with other astronomers at the December meeting of the American Geophysical Union in San Francisco, and in the journal Earth and Planetary Science Letters. So far, Kasting’s team has only shown that such an explanation is possible. But the researchers say field trips could help test the idea by looking for evidence of multiple warm events, and their duration.

【推荐3】Going to outer space is a little like going camping. Food with all the water dried out is lightweight and doesn’t spoil(变坏). So, many space foods are dried on Earth and stored in special packets.    1    

On Earth, gravity is the force that keeps your feet on the ground and your sandwich on your plate.    2    . To keep food from floating(漂浮) away, astronauts on the Space Shuttle attach the packets to a special tray(托盘). The tray can be fixed to a wall or to the astronaut’s lap. To prepare their food, astronauts use liquid forms of salt and pepper. The liquid sticks to the food better. Regular salt and pepper would float away, maybe up an astronaut’s nose.

    3    So astronauts drink everything from a small bag with a straw(吸管) that can be closed. Astronauts say that most space foods taste pretty good.

Some, such as apples and pudding, are the same as the foods you eat on Earth. Astronauts eat tortillas instead of bread because they make fewer crumbs(碎屑).    4    .Your body uses food in space the same way it does on Earth. Your body must deal with waste in space too.

During take-off and landing, astronauts can’t leave their seats to go to the bathroom. They wear diapers(尿布) under their spacesuits instead. The Space Shuttle has a bathroom the size of a small closet. The toilet has bars that keep astronauts from floating away.     5    

【推荐1】Mary Wilkins Ellis was a volunteer pilot for Britain's Air Transport Auxiliary( ATA) during World War II.

Mary Wilkins was born on Feb.2, 1917. When she was 8, her father bought her a ride in a plane. From there, she was hooked. As a teenager, she persuaded her father to pay for flying lessons, and she earned her pilot's license at 22 in 1939.

In 1940,she heard an ad for volunteer pilots to help the war effort. She signed up and joined the ATA, whose task was to deliver planes from factory to base or from base to factory for repairs.

At the height of World War II, 26-year-old Mary Wilkins climbed down a ladder from the cockpit (驾驶舱) of a bomber(轰炸机) at a Royal Air Force base in England.

“Where's the pilot?” someone on the ground asked.

“I am the pilot!” she responded. She had delivered the bomber alone-although built for a five-man crew-from its factory. People on the ground looked at her in surprise. One of them even decided to climb up the ladder to check the plane for the “missing” pilot.

She was one of the “Atagirls”, as they were nicknamed, who almost always flew without other crew members, compass or radio assistance. They guided themselves by using maps and following rives or railway lines. While they did not fly in combat(战斗), they faced the daily danger of attack by enemy planes. Mrs. Ellis was once shot at over Bournemouth, in southern England, by “friendly fire” from the ground. Another time, she had a near-miss when landing in thick fog at the same time a combat Spitfire landed on the same runway from the opposite direction. That experience won her the nickname “the fog flyer” .

In all, Mrs. Ellis flew more than 1,000 warplanes of 76 types-including 400 Spitfires-among more than 200 British airfields from 1942 to the end of the war in 1945.

【推荐3】In the Great Hall of the People in Beijing, hundreds of journalists were holding lights, cameras and voice recorders as they tried to find strategic positions at group interviews.

Each speaker was allowed only a short time. Everyone laughed because Professor Zhu Youyong carried along a big potato during his two minutes.

“Farmers in China’s poor areas can rely on agricultural science to strive for a well-off said the 63-year-old plant-disease expert.

Professor Zhu is nicknamed “potato scholar”. Born into a family of farmers in Yunnan, Zhu said he has an attachment with the land. Since 2016, Zhu’s team has promoted agricultural science in Lancang, Yunnan province.

Zhu said farmers in the area only planted rice once a year. After the harvest, the rice fields stayed unused for the entire winter. In 2016, his team launched a pilot program, a program which was used to test the idea of growing a late — season potato crop.

Success soon arrived, with about 3.1 tons of potatoes harvested in a field covering just one mu （0.07 hectare）, which brought income to farmers of about 9,000 yuan （﹩I,420）. Then in 2017, Zhu expanded cultivation （栽培）in several villages in the county, benefiting more than 1,000 families.

“We have set a goal of helping every poor farmer in the county to earn 10,000 yuan out of each mu of farmland cultivated each winter, so as to lift farmers out of poverty （贫困）," Zhu said.

"Ultimately, I am a fanner. Going back to the fields and seeing how my research changed the lives of farmers in China is the most important thing to me," he said.