I like getting up very early in summer. The morning air is so good________.

A.to be breathed

B.to breathe

C.breathing

D.being breathed

答案及解析： B

考查动词不定式主动表被动。在主语（物）+be+性质形容词（常见的有easy/difficult/hard/pleasant/possible等）+不定式结构中，不定式短语用主动表被动，例如：Russian is hard to learn.