It is known to all that we today's students fix our attentions on our lessons, so we know little of society. A holiday was the best time and the best chance to make up that. Taking a part-time job is a good form of social practice. What we have learned in books or in class can't have the same important effect on us as which we have learned through personal practice. In social practice, we can surely make a progress in both knowledge and practical abilities. However, when we take a part-time job, we may get paying more or less to help our family. Thus, I will say senior school students should take part-time jobs in our holidays, if it's possibly.

   In the United States a voluntary organization called Musician Corps is making a difference in people's lives. Five years ago，Kiff Gallagher，the founder of the organization，realized that music and public services could be used together to help Americans in need. Recognizing that music has a positive effect on Alzheimer's disease and autism（自闭症），he had the idea of creating Musician Corps.

Musician Corps looks for musicians and trains them as teachers. Then the musicians provide these services in city schools，children's hospitals，and assisted-living homes for older adults. They also help organize community concerts. Anyone can play music at these community activities.

Kiff Gallagher says what makes Musician Corps different from other charity organizations is that everybody can take part. It provides a place for people to get involved. He remembers a Musician Corps event at a hospital. Afterwards，he says，the patients are less depressed.

David Meletiche, one of 200 musicians in Musician Corps, teaches an after-school guitar class in a high-crime neighborhood. He is excited that the group gives him not only a job in a difficult economy but also the chance to use the team-building skills he gained in college.

There are 12 high school students in his class. Selena Makwan, one of them who are learning to play the guitar, says the program keeps her busy. "It definitely keeps me off the streets, because without this program I probably would be wandering around right now and I would not know what to do. And it also gives me an opportunity to learn something I' ve never done before."

Musician Corps has established programs in California and North Carolina. Kiff Gallagher hopes Musician Corps will continue to expand across America.

   Of all my dreams, my least favorite is the one where I'm in a car. It always begins with me driving, but eventually I realize that for some reason I'm sitting in the back seat. I can’t keep the car under control, rushing toward the roadside until, screaming, I wake up.

This is like the passenger experience in Waymo's self-driving cars. You sit in the back seat of a vehicle and watch as the wheel turns itself above an entirely empty driving seat.

''We made you live your nightmare, '' a Waymo staff member joked after I exited one of the company's fully self-driving car, following a quick drive inside its secret testing site. Waymo, a self-driving car company, arranged these rides for 40 journalists at this site.

There were also some demonstrations(演示). We watched as a Waymo car was cut off by a speeding vehicle. Then the employees created a situation in which a pile of moving boxes fell into the street just as another car passed in the opposite direction. Throughout the day, the cars performed impressively, driving with the level of care you might take if you had a wedding cake in the back seat.

During these demonstrations, Waymo gave information about what it was planning to do with these vehicles. The company has laid out four ways that its technology could be made available to the public. But Waymo's CEO, John Krafcik, wouldn’t show which of these was likely to come to market first, or on what kind of timeline.

I can't help but admire that Waymo is succeeding in developing this technology. There are countless possibilities at play on the road. The task of programming software to react to all those situations is unimaginably complex. What a great breakthrough!