题目

如图所示，物体重G=100N，用细线AC、BC和轻弹簧竖直吊起，处于平衡状态，弹簧的自然长度为L0=5cm，劲度系数k=8×103N/m，细线AC的长度为s=5cm，α=37°,β=53°。求细线AC的拉力有多大？  答案：F=156N解析:略 The bad weather discouraged us ______ on the picnic and we had to stay at home.A．from goingB．to goC．goD．in going