题目

 完形填空Do you like to visit the zoo in our city? Zoo is a good place ___(1)____. There is a zoo ____(2)___a river and a small mountain. It’s very big and there are a lot of tall trees in it. We can see a lot of golden fish(金鱼) in it, they have all kinds of ____(3)_____ . Some are red, some are yellow, some are white and some are black. They are swimming in the water. And they are very _____(4)_____.We can see a hill. About twenty ____(5)____ are playing on it. Some are asking people for ____(6)_____. The little monkeys are in their mothers’ arms. They are very interesting and ch已知三角形的三边分别n+1、n+2、n+3，当n是多少时，三角形是一个直角三角形？