题目

某同学做“验证力的平行四边形定则”的实验装置如图甲所示，其中A为固定橡皮条的图钉，O为橡皮条与细绳的结点，OB和OC为细绳．根据实验数据在白纸上所作图如图乙所示，已知实验过程中操作正确． （1） 乙图中F1、F2、F、F′四个力，其中力(填上述字母)不是由弹簧测力计直接测得的．实验中，要求先后两次力的作用效果相同，指的是(填正确选项前字母)．A．两个弹簧测力计拉力F1和F2的大小之和等于一个弹簧测力计拉力的大小B．橡皮条沿阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。I like taking photos very much. Once I travelled by ship 【1】 a cloudy morning. It was in the afternoon 【2】 the weather turned fine. Therefore, I wanted to take some 【3】 (photo). I was looking around and I saw next to me a lovely little girl sitting on her father’s shoulders. 【4】 was lucky for me 【5】 (meet) such a perfect moment—the girl was smiling and the surrounding view was beautiful. Without 【6】 （think）, I took a picture of 【7】 little girl at that moment.Her mother was 【8】 (surprise) that a stranger was photographing her daughter. I explained that I was moved by that sight and showed them the photo on my digital(数字的) camera. They loved it very much. I said I could email it to them when I got home. 【9】 (Final), they gave me their email address. The next day, I 【10】 (send) them their daughter’s photo as I had promised.