Short answers, pulled from the story.
The Chinese National Revolutionary Army launched a multi-front counter-offensive in the winter of 1939 to prevent Japan from launching new local offensives or shifting forces to concentrate against China. This operation marked the first major coordinated attack by Chinese forces during the Second Sino-Japanese War.
Chinese forces liberated the city of Kaifeng on December 16th after two weeks of fighting. They captured Japanese equipment before being pushed out again despite managing to retake the city.
The Chinese Army suffered 6,564 killed, 4,595 wounded, and 2,828 missing in the First Battle of Northern Guangdong from the 17th of December 1939 to the 10th of January 1940. The 4th War Area reported more than 10,300 enemy killed and captured large amounts of supplies.
Japan made heavy use of chemical weapons against China to make up for lack of numbers in combat. Their reliance on poison gas compensated for manpower shortages during the offensive and targeted both regular forces and specific Muslim units defending key regions.
Muslim Generals Ma Hongkui and Ma Hongbin defended west Suiyuan during 1940. Ma Hongbin commanded the 81st Corps which suffered heavy casualties but eventually repulsed the Japanese invasion plan.