The only solution to rubbish problem for a nation which now spends more on wrapping food than it pays farmers to produce it, is recovering______the packaging materials for commer cial as well as for conservation reasons.

A．on sale

B．on the spot

C．on a large scale

D．on all sides

案卷装订案卷厚度以不超过（）页或者20毫米为宜。材料过多的，应当按照顺序分册装订。

A、100

B、150

C、200

D、250