Time, Newsweek, and U. S. News & World Report are popular newsmagazines. The present national and international news, stories of human interest, and reports on new books, movies, plays, sports events, fashions, foods and so on are included. The articles are written in an informal style, and they are illustrated with photographs. More than nine million people read newsmagazines regularly. Two picture magazines Life and Look enjoyed popularity for many years. They presented the news with simple texts and many photographs, and they remained among the most widely read magazines until the late 1960s. Some people think these picture magazines were forced out of business because they could not compete successfully with the live pictures on televised news programs. Today there are approximately 1 750 daily newspapers, with a total circulation of over 62 million and more than 580 Sunday papers, with a circulation of almost 60 million.

1999年制定的固体矿产储量分类新标准中，将矿产资源分为储量、基础储量和资源储量三种，请答出它们三种储量的含义？