The library of congress in Washington, D.C., which【C1】______ the largest collection of boo
Air pollution and moisture【C5】______ the problem.【C6】______ , the books that are most【C7】______ destruction are not the oldest books. The paper in books produced【C8】______ the last century was made【C9】______ cotton and linen rags,【C10】______ are naturally low in acid. And the Gutenberg bible,【C11】______ five centuries ago, was made of thin calfskin, and is in【C12】______ good shape. But in the nineteenth century, with widespread literacy bringing a demand for a cheaper and more plentiful【C13】______ of paper, the industry began using 【C14】______ treated wood pulp for making paper.【C15】______ the chemical in these paper that is causing today's problem. This problem of paper deterioration is one of【C16】______ concern. France, Canada, and Austria are all doing research into the new methods of deacidification. A new technology has been【C17】______ recently, in fact, that allows for mass deacidification of【C18】______ books at the same time. It costs less than microfilming and 【C19】______ preserves books in their original form.【C20】______ there will soon be treatment facilities all over the world to preserve and deacidify library book collections.
【C1】
A.consists of
B.belongs to
C.houses
D.composes