【推荐2】In the Hollywood movie The Martian, actor Matt Damon plays an astronaut who ______ food on Mars to survive alone on the red planet.

After seeing the movie, physicist Michael Allen and food scientist Helen Joyner decided to carry out a case study helping students find out how to farm on Mars. Students have to ______ they are mining (采矿) on Mars and decided how to ______ themselves there before starting on the journey. They get ______ from Ellen and Joyner on how to choose and grow crops on Mars. Students use a scoring system to choose 3 foods to plant on Mars. Allen found the results ______ among 30 students, “No two people have ever gotten the ______ answer”, he said.

Human travelers to Mars will likely have to make use of resources on the planet rather than take everything they need with them off their ______. This means farming their own food on another planet.

One challenge for students is the fact that there can be no farming tools. Like real astronauts, students cannot take farming tools with them, as Joyner said, “You are starting with ______.” Besides, students also have to deal with very ______ choices of diet, “If I even had to eat a single food for the rest of my life, could I do it?” Joyner asked. But Ellen believes the case study is about more than farming and eating on the red planet.

“I’m not teaching about growing food on Mars,” Allen said, “I’m teaching about living with choices. I’m teaching about ______.”

【推荐3】Electricity is very useful in our daily lives. It is said to be one of the greatest________ in human history. It lights our world, ________ our homes, cooks our food and gives us lots of happiness. Electricity brings brightness. Today, almost everyone around the world uses electricity in one way or another. It is ________ to imagine our life without it. When the power is off, schools, offices, shops and factories cannot ________ at all. Without electricity, our________ would be very difficult. In large cities, electricity lights the streets and buildings. It warms people and ________. People can heat food in microwaves. Electricity also cools our food in________. Electricity drives underground trains, works traffic lights and lifts the machines in factories. Radios, televisions and computers use electricity to bring entertainment（娱乐）and news to millions of ________ every day. In the countryside, electricity also helps a lot. In villages and on farms, electrical machines milk the cows. They also cool the milk and keep it ________for us to drink. In fact, electricity is used as much in villages as it is used in ________.

Having failed twice before, Meng Jiao (751-814) passed the imperial examinations (科举考试) at the age of 46. He shows his wild joy by saying that the ________ he experienced before are no longer worth mentioning. Now he ________ confidence and energy, riding his horse along the flower-filled streets of Chang’an. He feels the spring breeze (微风), the wide sky, and the open road, and ________ his horse is running faster. In the city of Chang’ an, many flowers are ________ in spring, but he has seen them all in one day! The poet connects his joyful feelings with the scenery and expresses them in a clear and ________ way. The last two lines have become ________ throughout the ages.

Hilda Conkling’s poem suggests that joy cannot be seen, but rather felt through experiences in ________. She talks about how watching waves break or looking through violet stems (紫罗兰茎) in spring grass can give us feelings of joy. Also, joy comes from within a person and can be seen in their eyes, ________ being just a result of external