Libraries everywhere in the world have always been people’s only access to important sources of information. This historical function of libraries has worked out for centuries and has made libraries a necessity to people. Now, that function has been called into question by the fast development of digital media over the past several decades. In order to continue to hold the public interest, libraries everywhere are forced to develop means of granting access to these expensive new services to average people.
In the past, the publishing industry maintained the rights of libraries to freely provide published materials on the condition that libraries bought so many of their books. Since the new 
electronic publications can ea
sily be copied in their completeness by the library readers, the publishing industry is reconsidering its f
ormer support of the library system. There have even been attempts to stop libraries from delivering digital media.
In addition to the reluctant cooperation of the publishing industry, there is the problem that the newer forms of information are much more specialized than those which they replace. Deciding how to transfer already limited resources is increasingly difficult as there are more methods. While a single reference index(索引) might have covered an entire field in the past, now there are frequently several specialized indexes available in electronic form. Above all, in order to continue to make use of the newer technology, libraries must decide which kinds of material are most useful to the majority of their readers. There are many different solutions being applied, but only the process of trial and error will help find out the most effective method.
（Note: Answer the questions or complete the statements in NO MORE THAN 20 WORDS）
1. What has been called into question?
2. In the past, publishers cooperate with libraries because ______________.
3. The most important way to use the new technology is to determine ________
4. According to the passage, how can best solutions be found?
