With the word“PM2．5"_____appearing in media reports，people pay greaterattention to it and seek health tips for smoggy days．

Only __________ one loses freedom __________know its value．

He once observed that “All happy families ______ one another, but each unhappy family isunhappy in its own way”.[ ]

What’s this ____ a quilt.

Does it often rain here in summer?— Hardly ever ,____, the climate is like that of a desert.[ ]