it's the dangers parents can't quantify that occur all of a sudden.辛苦了!
问题描述：
it's the dangers parents can't quantify that occur all of a sudden.辛苦了!
答
这是一个强调句型,it is .that...
主句是 It's the dangers that occur all of a sudden.
all of a sudden是状语,修饰occur
正是这种危险事件会出其意料地发生
parents can't quantify是省略了关系代词that的定语从句,对dangers 作出了限定
整句翻译：正是这种父母不能估量的危险事件会出其意料地发生.