During world war ii, what happened between the communists and nationalists in china?

they continued their civil war but also fought together in world war ii.
their civil war raged while they avoided involvement in world war ii.
both sides agreed to stop fighting each other until world war ii ended.

Lien's trip to China is the first of a KMT leader since the nationalists took refuge on the island to escape the advance of Mao Tse-tung's communist troops in 1949 and the separation of Taiwan from the mainland. The two leaders clasped their hands for a few minutes in front of the cameras. "I welcome him warmly," Hu Jintao said before receiving his guest's thanks.

During World War II, Chinese communists and nationalists came together to confront the Japanese occupation, but at the end of the conflict, in 1945, they again faced each other.

The civil war between the two sides culminated in 1949 with the separation of mainland China, governed by the Chinese Communist Party (CCP), and Taiwan, where the Kuomintang took refuge.

We can say, Both sides agreed to stop fighting each other until World War II ended.