问题
选择题
| The children ______ many times not to swim in the river. |
A. told B. have told C. have been told D. are being told |
答案
答案：C
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| The children ______ many times not to swim in the river. |
A. told B. have told C. have been told D. are being told |
答案：C
位置时也恰好平衡，在A位置水平杆受到的压力为
，细线的拉力为
，在
位置水平杆受到的压力为
，细线的拉力为
，则下述结论正确的是（ ）
，
，
，
，