题目

在“互成角度的两个力的合成”实验中，橡皮条的一端固定在A点，另一端被两个弹簧秤拉到O点，如图甲所示．两弹簧秤读数分别为F1和F2，细绳方向分别与OA直线延长线的夹角为α1和α2，如图乙所示．以下说法中正确的是（     ）                              A．  O点位置不变，合力不变    B．  用平行四边形定则求得的合力F一定沿OA直线方向    C．  若不改变O和α1，F1增大，F2必减小    D．  合力必大于F1或F2              完形填空I have two friends, Lucy and Lily. They are , but they are different. Lucy likes music. She can play piano. She often helps me my homework. She speaks English . Lily likes sports. She plays tennis every day. she thinks it’s . She often plays sports me. They both get up 6:30. They eat fruit and vegetables for lunch. They have a life. They go to school bus. It takes about 10 minutes to school. Their father is a math teacher. They love very much.1.A、sisters B、sister C、brother2.A、a B、the C、×3.A、do B、doing C、does4.A、good B、well C、is good5.A、× B、the C、a6.A、Because B、So C、But7.A、boring B、relaxing C、late8.A、for B、about C、with9.A、at B、in C、on10.A、lot of B、many C、a lot of11.A、health B、unhealthy C、healthy12.A、take a B、by C、by a13.A、them B、they C、their14.A、get B、to get C、getting15.A、her B、he C、him