短文填空请用适当的词完成下面的短文，并把所缺单词填写在答题卡指定的位置上。每个孔只能填写一个形式正确、意义相符的单词。
The Great Wall is known as the eighth wonder of the world. Every year thousands of tourists from all over the world come to visit this place of ____ in China.
Last Saturday I went to theGreat Wall ____ some of my friends. It was a sunny day. On our way up, we saw many volunteers(志愿者) keeping working in the sun. They helped the elders with their bags., ____ photos for some tourists and answered people’s questions. Though they are very____ , they didn’t stop to have a rest. We were deeply moved when we saw this.
Just at the moment, we saw ____ little boy standing alone and crying. We went over and asked what ____ to him. From his answer we knew that he couldn’t find his mother. We told him not to ____ about it and then we tried to get to touch with his mother with the phone number he gave us. Twenty minutes ____ , his mother turned up. When she saw her son, she was very excited and thanked ____ with tears in her eyes.
That day we not only enjoyed the beauty of the Great Wall, but also felt the warmth of the society. ____ everyone can reach out a helping hand to others, the world will be more and more harmonious(和谐的).
是椭圆
上的一点，
、
为焦点，
，则
的面积为
（ ）