This is the concert hall__________ I lost my backpack.

Some people like wearing fashionable clothes;______, some birds like bright feathers.

__________ I have a look at your new e-book—I am sorry. I can’t find it. My mother ______ have taken it. But I am not sure.

Environment(环境) is very________，but you don’t understand the_______ of it，you always drop litter everywhere．

Water is the cheapest drink. And it is also ______.