A:减少各种热损失
B:加润滑油,减少机器部件的摩擦
C:减少消耗的总能量
D:充分利用废气的能量,如建热电站
Hello! I'm Dolly. ①I work at a hospital. ②I'm a nurse. My house is not far from the hospital. ③So I walk to work.④And my brother is a teacher.⑤He goes to work by car.
①____ ②____ ③____
④____ ⑤____
A. How does he go to work?
B. Where do you work?
C. What does your brother do?
D. How do you go to work?
E. What do you do?
They ____ by the ____ last weekend.
大型历史纪录片《大国崛起》的解说词中有这样几句话:“三百年前,人类的思想还充斥着迷信和恐惧,水为什么往低处流?太阳为什么升起落下?这些今天看来简单至极的问题,在当时却是根本无法认识和把握的。”这些在“当时却是根本无法认识和把握的”问题,终于被人类破解的标志性科学成就是 ( )