Insulin can be extracted by buffered acetone solution.

A、

B、

C、

D、

A、sulfuric acid

B、nitric acid

C、palmitic acid

D、salicylic acid

In such a changing, complex society formerly simple solutions to informational needs become complicated. Many of life's problems which were solved by asking family members, friends or colleagues are beyond the capability of the extended family to resolve. Where to turn for expert information and how to determine which expert advice to accept are questions facing many people today.

In addition to this, there is the growing mobility of people since World War II. As families move away from their stable community, their friends of many years, their extended family relationships, the informal flow of information is cut off, and with it the confidence that information will be available when needed and will be trustworthy and reliable has lost. The almost unconscious flow of information about the simplest aspects of living can be cut off. Thus, things once learned subconsciously through the casual communications of the extended family must be consciously learned.

Adding to social changes today is an enormous stockpile of information, The individual now has more information available than any generation, and the task of finding that one piece of information relevant to his or her specific problem is complicated, time-consuming and sometimes even overwhelming.

Coupled with the growing quantity of information is the development of technologies which enable the storage and delivery of more information with greater speed to more locations than has ever been possible before. Computer technology makes it possible to store vast amounts of data in machine-readable files, and to program computers to locate specific information, Telecommunications developments enable the sending of messages via television, radio, and very shortly, electronic mail to bombard people with multitudes of messages. Satellites have extended the power of communications to report events at the instant of occurrence. Expertise can be shared worldwide through teleconferencing, and problems in dispute can be settled without the participants leaving their homes and/or jobs to travel to a distant conference site. Technology has facilitated the sharing of information and the storage and delivery of information, thus making more information available to more people.

In this world of change and complexity, the need for information is of greatest importance. Those people who have accurate, reliable up-to-date information to solve the day-to-day problems, the critical problems of their business, social and family life, will survive and succeed. "Knowledge is power" may well be the truest saying and access to information may be the most critical requirement of all people.

The word "it" ( Line 3, Para. 2) most probably refers to ______.

A．the lack of stable communities

B．the breakdown of informal information channels

C．the increased mobility of families

D．the growing number of people moving from place to place