A:小球受到重力和绳的拉力
B:小球受到重力、绳的拉力和斜面的弹力
C:小球受到重力和和斜面的弹力
D:小球只受到重力作用
在做“探究影响鼠妇分布的环境因素”的实验时,用的鼠妇数量最合适的是( )
A. I want to buy some toys.
B. Go straight down this street. Turn left at the traffic lights.
C. Sure.
D. He is flying a kite.
E. They played basketball.
25×34﹣(﹣25)×12+25×14.