问题
猜谜题，问答题
根据实际情况回答问题。
1. Are you as tall as your mother?
2. What did you do last weekend?
3. Are there any public signs in your school?
4. Is it often rainy in summer in Nanjing?
答案
1. Yes, I am. 2. I went to shopping with my mother.
3. Yes, there are some public signs. 4. Yes, it is. （答案不唯一）
型均匀杆总长为3L，AB水平，BC⊥AB，杆在竖直平面内可绕水平轴O转动，若在杆的右端A点加一方向竖直向下的力F，使AB顺时针缓慢转600过程中，以下说法正确的是（ ）