More than 2,000 years ago, ancient Chinese people created an overall framework to mark the annual passage of time based on observations of the sun’s motion, called ___________. （ ）

题目：More than 2,000 years ago, ancient Chinese people created an overall framework to mark the annual passage of time based on observations of the sun’s motion, called ___________. （ ）

“the 12 Chinese zodiac signs”
“5 great mountains”
“the 24 solar terms”
“5 famous lakes”