已知圆心C（1，3），圆上一点A（﹣4，﹣1），求直径AB的另一个端点B的坐标．

按要求写句子。

谭老师的姿势震撼了抢险人员。（改成把字句）

①***独立领导革命战争的开始②创建人民军队的开始

③建立农村革命根据地的开始④国共合作的开始

       It was June. The sun was in the sky. It was very hot. Jim was tired of school. He wanted to be at the beach. He could not stay in his  1 . He could not   2 talking. While the teacher wrote on the board, Jim got up and talked to a friend. The teacher, Mr Smith, heard the 3 and said: "Jim, sit down and be quiet. "
       Jim sat down. Mr Smith  4 his lesson. Jim got up and talked to another friend. "Sit down and be quiet," said Mr Smith. He was very  5 .
    "OK," said Mr Smith.  "If you want to talk, 6 come to the front of the classroom and 7 the teacher. "
    "All right," 8 Jim. He came to the front of the classroom and said:"Quiet,9 . I am the new teacher. Class is over now. Let's have a 10 "

如图，一质量为M=1kg的光滑大圆环，用一细轻杆固定在竖直平面内；套在大环上质量为m=0.2kg的小环（可视为质点），从大环的最高处由静止滑下．重力加速度大小为g．当小环滑到大环的最低点时，大环对轻杆拉力的大小为（   ）