夏季是消化道传染病的高发季节，学校食堂应加强食品卫生管理，及时消毒餐具．下列属于消化道传染病的是（　　）

6年前,刘靖放弃了城市里的企划工作,来到右玉县新城镇邓家村当了一名大学生村官。如今,大家已经不再叫她“大学生”,而是尊敬地称她一声“副镇长”。刘靖说,当大学生村官的每一天,自己都过得忙碌而充实。她知道,选择了农村,就意味着奉献。“远离了都市的繁华、城市的喧嚣,从某种意义上讲,好像是失去了一些东西,但这一具有划时代意义的大舞台更能让我全面地实践自我,让我的青春更加绚丽多彩。”刘靖这样评价自己的“得失”。

条件甲：“$a>0$且$b>0$”,条件乙：“方程$\frac{x^2}{a}-\frac{y^2}{b}=1$表示双曲线”，那么甲是乙的（ ）

根据短文内容回答下列各问题。

    Ma Hua graduated from Fudan University. He had a good career in IT and a great life in Shanghai, but he felt there was something missing from his life. He wanted to help others to improve their lives, so in March 2013 he gave up his job. Then he moved to south-west China to do voluntary work in a village primary school.

    He soon became an important member of the local people. In his class, he painted pictures on the walls to help students remember English words. He also spent his money building a playground for the children.

    Ma Hua quickly got used to his new life. He got great satisfaction(满意) from his work and felt very happy, even though life there was hard---he had to melt(融化) ice for water and grow vegetables for food. When he was free, he wrote poems describing the peace and beauty around him. Sometimes he would go walking in the mountains and enjoy the beautiful view. Sadly Ma Hua was killed in a car accident in July 2014 at the age of 31. His death was a great loss to all those who knew him, but it is a comfort to know that he lived happily, doing what he loved and enriching the lives of others.