B. Shaanxi-Gansu-Ningxia Border Region First \n

C. The slogan is "Do it yourself, have plenty of food and clothing" \n

D. the 359th brigade transformed Nanniwan.

Answer:

Accelerated business collection and delivery system (adopted by the United States post office)

Analysis:

From 1940 to 1943, serious economic difficulties appeared in the anti-Japanese base areas. Mao Zedong put forward "developing production and ensuring supply" and "do it yourself and have plenty of food and clothing" to launch a large-scale production campaign. First, it was carried out in the Shaanxi-Gansu-Ningxia border region (the 359th Brigade of the Eighth Route Army transformed the deserted Nanniwan into "a good south of the Yangtze River in northern Shaanxi"). The base areas overcame economic difficulties through large-scale production campaigns. \n