Mary Krupa became friends with the grey squirrels during her first week at Penn State, after spotting them running around and idly (漫无目的地) wondering what they would look like with tiny hats on their heads. Today, everyone at the university knows her as the "Squirrel Girl".

Mary started bringing them food, and gradually they began to trust her. She managed to put a hat on a squirrel and take a picture. Thinking that her colleagues could do with something to lift up their spirits, she started posting similar photos on Facebook. The response was greatly positive, and before long Mary and her squirrels became an Internet hit.

Growing up in a neighborhood outside State College, Mary was always fond of birds and animals around her home, but she didn't interact with people very much. She was later diagnosed with Asperger's syndrome, but the squirrels changed that. "The squirrels are actually a good way to break the ice, because I'll be sitting here patting a squirrel and other people will come over and we'll just start like feeding the squirrels together and chatting about them," she said. "I am a lot more outgoing."

And in case you're wondering how Mary is able to get the squirrels to do what she wants for her photos, it has a lot to do with food. For example, whenever she wants them to hold or play with something, she puts peanut butter on the prop (道具), and they'll grab it. But getting to that part took a while. In the beginning, she would throw peanuts up the trees on campus and invite the squirrels to come down and get them, but they hesitated to approach her. She had the patience to earn their trust, though.

This year, Mary is graduating with a degree in English and wildlife sciences. She wants to be a science writer and educate people on how to preserve the environment. As for her furry friends, Mary plans to stay in the area and visit them as often as she can.

A small family approached. The daughter was young and pretty. Her name was Blair, and she was obviously leaving. Her parents were not. The three gazed at the crowd and began their wait. Blair was twenty-three, fresh from graduate school with a handsome resume (简历) but not ready for a career. A friend from college was in Africa as a volunteer for Peace Work, which had inspired Blair to devote the next two years to helping others. Her assignment was in eastern Peru, where she would teach primitive little children how to read. She would live in a hut with no modern conveniences, no electricity, no phone, and she was anxious to begin her journey.

The flight would take her to Miami, then to Lima, then by bus for three days into the mountains, into another century. For the first time in her young and sheltered life, Blair would spend Christmas away from home.

Luther, her father, was sad that Blair was leaving. The goodbyes had all been said. "Are you sure this is what you want?" had been asked for the hundredth time. Then, the first announcement was made, the one asking those in first class to come forward.

"I guess we'd better go," Luther said to his daughter, his only child. They hugged again and fought back the tears. Blair smiled and said, "The year will fly by. I'll be home next Christmas."

Nora, her mother, bit her lip and nodded and kissed her once more. "Please be careful," she said because she couldn't stop saying it.

"I'll be fine."

They released her and watched helplessly as she joined a long line and inched away, away from them, away from home and security and everything she'd ever known. They turned and got into endless sadness.

One night, when I was eight, my mother gently asked me a question I would never forget. "Sweetie, my company wants to1me but needs me to work in Brazil. This is like your teacher telling that you've done2and allowing you to skip a grade (跳级), but you'll have to3your friends. Would you say yes to your teacher?" She gave me a hug and asked me to think about it. I was puzzled. The question kept me4for the rest of the night. I had said "yes" but for the first time, I realized the5decisions adults had to make.

For almost four years, my mother would call us from Brazil every day. Every evening I'd6wait for the phone to ring and then tell her every detail of my day. A phone call, however, could never replace her7and it was difficult not to feel lonely at times.

During my fourth-grade Christmas break, we flew to Rio to visit her. Looking at her large8apartment, I became9how lonely my mother must have been in Brazil herself. It was then10I started to appreciate the tough choices she had to make on11family and work.12difficult decisions, she used to tell me, you wouldn't know whether you made the right choice, but you could always make the best out of the situation, with passion and a13attitude.

Back home, I14myself that what my mother could do, I could, too. If she15to live in Rio all by herself, I, too, could learn to be16. I learn how to take care of myself and set high but achievable17.

My mother is now back with us. But I will never forget what the18has really taught me. Sacrifices (牺牲)19in the end. The separation between us has proved to be20for me.

Many teachers believe that hands-on experience is the  (good) way to learn. A group of students in the United States are putting that belief to the test. They  (success) designed and built a robot for discovering unexplored mines  the bottom of the sea. Students made the robot  (answer) a challenge from the U. S. Department of Defense.

The students recently tested the underwater vehicle  (call) Perseus Ⅱ in a 95-meter-long tank of water at the Stevens Institute of Technology.

The robot costs about $15, 000 to build. The students use a video game control to direct (it) movements in the tank. What's more, devices known as Japters  (able) the robot to go up, down and toward its target in the water. Video cameras on the robot send images back to a computer through a 13-meter-long cable. Perseus Ⅱ,  the students worked up to 20 hours a week to design and build, also has  set of lasers (激光), which are used to measure the size of an object.

DeLorme supervised the project from  (begin) to end. He says the specialized requirements of robots were demanding.