小芳面向穿衣镜站立在镜前1m处，她在镜中的像距离平面镜　 ____　 m；当平面镜平行于小芳左右移动时，以小芳为参照物，像是 ____（选填“运动”或“静止”）的．

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    My name is Sally. There are 1 people in my family. My grandfather 2Mike. His birthday is 3 February 7th. My 4 name is Alan. August 5 is his birthday. My grandmother is Jane. 6 birthday is on April 8th. My mother's name is Jenny. Her birthday is 7 September. Do you know(知道) 8 my birthday is? Oh, 9 on November 26. I like to go mountain 10 on that day.

一物体受到大小分别为3N和4N两个力的作用．当这两个力方向相同时，合力大小为____N；当这两个力相互垂直时，合力大小为____N．