3, She wanted to find out whether it would be comfortable to wear.

动词不定式to wear, 用来修饰说明comfortable,  作它的状语

e.g. The book is difficult to read.

e.g. The dress is easy to wash.

e.g. Your handwriting is easy to recognize.

主动形式表达被动概念的形式：

（1）adj. + 不定式

e.g. The music is sweet to hear.

（2）用need, want和动名词形式直接搭配

e.g. The machine needs repairing.

(3) worth doing 值得做某事

e.g. The dictionary is worth buying.\e.g. The book is worth reading.新概念英语第四册

（4）under＋n. 在…之下（抽象）

e.g. The house is under construction.\e.g. The puma is under control.

e.g. The problem is under discussion.\e.g. The thief is under arrest.

（5）came into use, go to waste等不及物动词短语

e.g. The airport came into use again.

e.g. Our time has already gone to waste. （浪费掉，付诸东流）

（6）-able 形容词后缀，跟在动词后表达“能够被…的“

e.g. She is a respectable person. (被尊敬的人)

e.g. This is a returnable bottle. 这是个可回收的瓶子。

（7）“由…所组成”：consist of, comprise 本身表达被动概念，结构形式为主动。

e.g. The team consist of one Chinese and two Americans.