The answer is the mystery of the winter solstice.

Mystery: the mountains are vast in the fog, and the city heads are dotted. (Make a solar term)

Answer: the solstice in winter.

Mystery: Arrive after autumn. (Make a solar term)

Answer: the solstice in winter.

Mystery: just want to get along with each other? (Make a solar term)

Answer: Solstice in winter

Mystery: can spring be far behind? (Make a solar term)

Answer: Solstice in winter

Riddle: Are you ready? (Make a solar term)

Answer: Solstice in winter

Mystery: tear down the frame? (Make a solar term)

Answer: Solstice in winter

Mystery: Is there a cloud moving in the picture? (Make a solar term)

Answer: Solstice in winter

Finally, I wish my friends a happy winter solstice and a warm and peaceful holiday.