题目

补全对话。A: Jack, I went to Beijing with my family last month.B: Really? A: It was wonderful! B: How did you get there?A: B: Did you stay there long?A: Hmm, only three days. But I found people there are friendly.B: A: We visited the Great Wall, the Palace Museum and some other well-known places.B: A: Yes. It's very nice and tastes delicious.A. I had a great time. B. By high-speed train.C. How was your trip? D. What places of interest did you visit?E. Were you used to the food there?跳伞运动员在从飞机上跳下、降落伞没有打开之前，下落会越来越快，此时运动员受到的阻力________重力；当降落伞打开后，运动员匀速下落时，受到的阻力________重力。（选填“大于”、“小于”或“等于”）; 某同学沿水平向南用20牛顿的力推着一辆车匀速前进，小车受到的阻力是______牛顿; 小车在竖直方向受到_________和____________ 的作用，它们是一对平衡力。