-------of the two families have happy life.(All,Both)用both 为啥

-------of the two families have happy life.(All,Both)用both 为啥
-------of the two families have happy life.(All,Both)用both 为啥

-------of the two families have happy life.(All,Both)用both 为啥
Both
two families 必须用both
both = 两个都
两个家庭都

对，填both
both of 表示两者都 。。
all of 表示三者或三者以上都。。
题中是“两家人都过着幸福的生活”，所以用both