问题
选择题
设定点F1（-3，0）、F（3，0），动点P满足条件|PF1|+|PF2|=6，则点P的轨迹是（ ）
A．椭圆
B．不存在
C．椭圆或线段
D．线段
答案
由题意可得：动点P满足条件|PF1|+|PF2|=6，
又因为|F1F2|=6，
所以点P的轨迹是线段F1F2．
故选D．
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设定点F1（-3，0）、F（3，0），动点P满足条件|PF1|+|PF2|=6，则点P的轨迹是（ ）
A．椭圆
B．不存在
C．椭圆或线段
D．线段
由题意可得：动点P满足条件|PF1|+|PF2|=6，
又因为|F1F2|=6，
所以点P的轨迹是线段F1F2．
故选D．
The day was Thankful Thursday, our “ regular day” of service. It’s a __36__tradition that my two little girls and I began years ago. On this __37__ Thursday, we had no idea exactly what we were going to do. __38__ along a busy road, we prayed for guidance in search of __39__our weekly Act of Kindness. My girls were__40__, and started shouting “ McDonald’s” . Suddenly I realized that almost every crossing I__41__ was occupied by a beggar, and then it hit me! All these beggars must be hungry. Perfect! We were going to buy__42__for them. It was a great way to__43__. The Act of Kindness was anonymous(匿名的)，and we loved what we saw in the back view mirror: a__44__and delighted person holding up his lunch bag and just looking at us__45__we drove off. We had come to the end of our “ route” where there was a small woman standing there, asking for__46__. We handed her our final lunch bag, and then made a U-turn to head back in the opposite direction for home. Unfortunately, the light stopped us. I was __47__and didn’t know quite how to behave. “No one has ever done anything like this for me before,” the woman said with__48__. I replied, “Well, I’m glad that we were the first one.”__49__ uneasy , and wanting to move the conversation along, I asked, “So, when do you think you’ll eat your lunch?” “Oh honey, I’m not going to__50__this lunch.” I was confused , and she continued , “I have a little girl of my own at home and she just __51__ McDonald’s , but I can never buy it for her because I just don’t have the __52__ . You know what… tonight she is going to have McDonald’s !” So many times I had__53__whether our Acts of Kindness were too small or insignificant to really__54__any difference . Yet in that moment, I recognized the__55__of Mother Teresa’s words, “We cannot do great things---only small things with great love.”
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