一个英语句子,看不懂居句式结构,Unhappy parents rarely are provoked to wonder if they shouldn’t have had kids,but unhappy childless folks are bothered with the message that children are the single most important thing in the world:obviously their misery must be a direct result of the gaping baby-size holes in their lives.主要帮助我分析一下句式结构,

两个并列主句，其中一个由but连接引导。第一句带有一个if引导的条件状语。
第二句的主句是unhappy childless folks are bothered with the message；
后面是一个定语从句that children are the single most important thing in the world:
然后是一个修饰全句的状语从句 obviously their misery must be a direct result of the gaping baby-size holes in their lives.

前两句是并列关系，最后那句与前两句之间是 结果状语

Unhappy parents rarely are provoked to wonder这是主句部分；if they shouldn’t have had kids这个是做wonder的宾语成分,因此事宾语从句；but unhappy childless folks are bothered with the message that children are the single most important thing in the world:obviously their misery must be a direct result of the gaping baby-size holes in their lives.这整个部分是和前面部分并列的,称并列句.unhappy childless folks are bothered with the message这是后面部分的主句.that children are the single most important thing in the world:这个部分是做message的同位语成分,起解释说明的作用.obviously their misery must be a direct result of the gaping baby-size holes in their lives.这部分是同位语从句中的一部分.
不知道这样你看明别没有啊?

冒号后面意思理解不透.不过句子成份的话也不难啊.
but前是个完整句子.but 后是个完整句子.
冒号(表明前面but前后不同现象的解释或者总结)后面也可视为完整句子~