问题
选择题
Mary got up late this morning _____ she didn't catch the first bus. [ ]
A. because
B. for
C. so
答案
答案：C
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Mary got up late this morning _____ she didn't catch the first bus. [ ]
A. because
B. for
C. so
答案：C
在探究“杠杆平衡条件”的实验中，若杠杆在使用前左高右低，要使它水平平衡，应将杠杆左端的平衡螺母向 调节。某小组得到的两组实验数据如下表所示：
| 动力F1/N | 动力臂Ｌ1/cm | 阻力F2/N | 阻力臂Ｌ2/cm |
| 2 | 5 | 1 | 10 |
| 1 | 6 | 2 | 3 |