地球绕太阳公转一周的时间是（ ）。
A：24小时
B：一个月
C：一年
A. He is playing ping-pong.
B. They are climbing trees.
C. She is singing and dancing.
D. I'm doing my homework.
E. It's running on the grass.
78−35+18−25 =____
请你谈谈“军民鱼水一家人”如何理解？
