设函数f(x)＝sin(wx＋$\frac{2\mathrm{\pi }}{3}$)＋sin(wx－$\frac{2\mathrm{\pi }}{3}$)(w＞0)的最小正周期为π，则（   ）

磁性水雷是用一个可以绕轴转动的小磁针来控制起爆电路的，军舰被地磁场磁化后就变成了一个浮动的磁体，当军舰接近磁性水雷时，就会引起水雷的爆炸，如图所示，其依据是（  ）

     Mr. Baker was a strong man. He liked playing football and spent a lot of time on the game when he studied in a medical college. But his right leg was broken when he was playing football with his friends. He couldn't play football any longer. He was sorry for it and still liked to watch the game.

      Now Mr. Baker works in a hospital. He is a good dentist and many patients ask him for help. He is always busy and has little time to watch the matches. He has to watch them on TV at home in the evening. But the biggest football match in their city would start at four one afternoon. Mr. Baker hoped to watch it, but the head of the hospital didn't agree. "You can't go out until all the patients in your office leave. " he said.

     It was three twenty when there were about ten patients in the waiting-room. Mr. Baker was worried. He thought for a moment and had an idea. He said to a woman who was lying on the dental chair,"Cry loudly,Madam! I'll pull your bad tooth out for free if you frighten away the other patients!"

根据短文内容，判断句子正误。

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    按照以下提示，写一篇作文，60词左右。假如你是吉姆。上周，你和你的同学乘公共汽车去了北海公园。天气晴朗，风小。你们钓鱼、照相、在树下做游戏、听老师讲故事、划船。中午在公园里吃午饭，下午三点半回家。同学们都很兴奋，玩得很高兴。