题目

已知双曲线的右焦点为，过点向双曲线的一条渐近线引垂线，垂足为，再反向延长交另一条渐近线于点，若，则双曲线的离心率为         . 答案：  I am fromIndia.Indiais a large country in southern Asia. It has the second-largest (第二大的) population in the world. People in India speak 16 different languages. The main language in our country is HindiC印地语) .Do you know Indian food? Indian people think if it's hot,it's good. My favourite food is lamb (羊羔肉) with bread and spice. I think it is the most deli?cious food in the world.Only about one-third of the people inIndiaknow how to read and write. Some parents only send their sons to school. I am very lucky because I know-how to read and write. The Indian elephants are very famous around the world. They eat many kinds of fruits,like ba?nanas. An elephant eats between 330 and 350 pounds of food and drinks lots of water each day. So they have to travel to new places to get new food and wa?ter. A mother elephant always takes good care of her baby. When she is away,other elephants will look after her baby.IndiaPopulationIt has the 36.      population in the worldLanguagePeople     can   speak   16 different languages, but the main language is 37.         .FoodIndian peopel like 38       foodEducationOnly about one-third of   the people know how to read and write. Some parents don't let their 39.       go to school.AnimalsIn India, the animals   famous around the world are   40.       .