16.I wonder why he didn’t come to school. He ___have been ill.

16.I wonder why he didn’t come to school. He ___have been ill.
16.I wonder why he didn’t come to school. He ___have been ill.

16.I wonder why he didn’t come to school. He ___have been ill.
应填might（虚拟）

16.I wonder why he didn’t come to school. He must have been ill

may

might
might have done表示虚拟，意思是：可能发生却未发生某事。
这样句子就通了：我想知道他为什么没来上学，他不可能生病的啊！
而用may则不够通顺：我想知道他为什么没来上学，他有可能生病了…

may
由前面的wonder想知道可知，猜测他可能生病了