题目

 Jean is a bright young woman who comes from a rich and famous family. She goes to a good university(大学) and has everything that money can buy. The problem is that the people in Jean’s family are so busy that they can almost not find time to be with her. In fact, Jean is quite lonely. So Jean spends a lot of time on her QQ. She likes being anonymous(匿名), talking to people who do not know about her famous family and her rich life. She uses the name Linda on QQ and has made a lot of friends who she talks with them quite often. Last year Jean made a very special friend on QQ. H每年的12月至次年3月期间都是人感染禽流感高发时段，2017年禽流感再次来袭。为控制H7N9的进一步蔓延，我们应该怎么做呢？根据所学知识，回答以下问题： （1）从传染病的起因看，H7N9禽流感病毒属于____________；（2）从传染病流行的三个环节来看，给家禽注射H7N9禽流感疫苗能有效预防H7N9禽流感病，该措施属于_____________。以此获得的免疫属于________免疫。