Mr. and Mrs. Wang invited Mr. and Mrs. Li and Mr. and Mrs. Zhang to their family dance. No man danced with his wife at the dance. Xiao Wang invited Xiao Li to dance. Xiao Li's partner is Xiao Zhang's wife, and Xiao Ying's husband is dancing with Xiao Lan.
Then Mr. and Mrs. Wang, Mr. and Mrs. Li and Mr. and Mrs. Zhang are respectively:
Xiao Wang-Xiao Lan, Xiao Li-Xiao Li, Xiao Zhang - Xiao Ying