Life must have been difficult when you were a kid.句子分析从句when you were a kid是个明显表示过去的从句,那么主句为什么用现在完成时“have been ...”呢?为什么不说：Life must be difficult when you were a kid.
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Life must have been difficult when you were a kid.句子分析从句when you were a kid是个明显表示过去的从句,那么主句为什么用现在完成时“have been ...”呢?为什么不说：Life must be difficult when you were a kid.
Life must have been difficult when you were a kid.句子分析
从句when you were a kid是个明显表示过去的从句,那么主句为什么用现在完成时“have been ...”呢?为什么不说：
Life must be difficult when you were a kid.
Life must have been difficult when you were a kid.句子分析从句when you were a kid是个明显表示过去的从句,那么主句为什么用现在完成时“have been ...”呢?为什么不说：Life must be difficult when you were a kid.
must have been和must be意思有所不同
must have been是对过去的事实的肯定猜测
must be是对现在事实的肯定猜测
如：She sings so well.I think she must have been a singer.
她唱得真好.我想她以前肯定是名歌手.
he doesn't come to school today. He must be ill.
他今天没有来上学,肯定是病了.
在这个句子里,正是由于状语从句中明显表示是过去,所以主句应该是对过去事实的猜测,因此要用must have been,而不能用must be
when you were a kid 是当你是个孩子的时候。过去式
must have been 还有表示肯定猜测。
也可以用when把两个一般过去时的句子连接起来。但是连接的条件是，从意思上可以明显看出后一动作跟随前一动作，二者并不是同时发生的