题目

任务型阅读 In our city, there is a big zoo. There are a lot of animals in it. Mona is an Australian koala. She is seven years old. She is very cute. She likes sleeping during the day. But at night she gets up and eats leaves. Mona doesn’t drink(喝)water for months. But she is healthy, because she can get water from the leaves. Here is a big house. A lion lives in it. His name is Gerry. He is ugly. He is from South Africa. Meat is his favorite food. Gerry is very lazy. He sleeps and relaxes for 20 hours every day. Today is Gerry’s eighth birthday. The workers in the zoo are having a某同学在学习了统计知识后，就下表所列的5种用牙不良习惯对全班每一个同学进行了问卷调查（每个被调查的同学必须选择而且只能在5种用牙不良习惯中选择一项），调查结果如下统计图所示．根据以上统计图提供的信息，回答下列问题：种类ABCDE不良习惯睡前吃水果喝牛奶用牙开瓶盖常喝饮料嚼冰常吃生冷零食磨牙（1）这个班有多少名学生？（2）这个班中有C类用牙不良习惯的学生多少人？占全班人数的百分比是多少？（3）请补全条形统计图；（4）根据调查结果，估计这个年级850名学生中有B类用牙不良习惯的学生多少人？