初二下册英语第五单元语法if条件从句怎样导入

对话导入就行.
老师假设一个情景,比如说,阿拉丁的神灯来了,并愿意给同学们每人一个愿望.
老师问：“If you have the chance,what will you do?”
假设学生说,“if i have the chance,i will be an astronout.”
老师接着问：“If you become an astronout,will you be happy?”
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这样问了几名同学之后,找一名同学向老师提问：“If you have the chance,what will you do?”
老师回答：,“if i have the chance,i will be an athlete.”
同学问：：“If you become an athlete,will you be happy?”
老师回答“i don't know.”由此引出标题——————If i become an athlete,will i be happy?