Strange Americans

I do not fully understand Americans. I wonder why they don't mind wasting food, plastic plateware, and energy. The most strange thing to me is that I often see people in a doctor's smock on campus. They eat outside or in a restaurant and go to school and go home in the smock. (By the way, the doctor's smock is green in the US.) The dress hygiene may not be strict, however, I feel discouraged about the moral of the future doctors.