How disappointed I was_____that the dancing party had been cancleled!A.learnedB.to learn C.to be learnedD.learning正确答案是：

How disappointed I was_____that the dancing party had been cancleled!A.learnedB.to learn C.to be learnedD.learning正确答案是：
How disappointed I was_____that the dancing party had been cancleled!
A.learned
B.to learn
C.to be learned
D.learning
正确答案是：

How disappointed I was_____that the dancing party had been cancleled!A.learnedB.to learn C.to be learnedD.learning正确答案是：
b
不定式做原因状语
得知舞会被取消的时候我是多么失望啊!

to learn
be xxx to do sth.
这是个强调句
正常的句子是：
I was disappointed to learn that the dancing party had been cancled.

A前面不能加to就能表示我得知舞会被取消的时候我是多么失望啊！

选D
learning that--从句作状语，状语从句中，动词一般采用ing形式，所以采用learning的形式而不是过去式和不定式。
整句的意思是：
得知舞会被取消的消息后，我特别地失望。