问题补充：
This is the craziest thing I have heard so far.间接引语“This is the craziest thing I have heard so far”（She thought).变成间接引语不是说只变从句吗？为什么答案中从句里的定语从句也要变？变成I had heard？为什么？
答案：
have heard与This is时态一致；现在is变成was,have当然要相应地变成had.
======以下答案可供参考======
供参考答案1:
这是我迄今所听过的最疯狂的事情
供参考答案2:
变成间接引语是指变成She thought的宾语从句，所以整句话(主句和从句)的时态都要前移，This is变成this was,have heard变成had heard,同时人称也要变。应为She thought this was the craziest thing she had heard so far.
供参考答案3:
很简单的！时态要一致嘛，一变都变
